refactor(8.0): final cleanup — drop HnswProvider alias + config.hnsw + 'hnsw' surface (scaffold step 6)

Step 6 of the brainy 8.0 rename scaffolding. Removes every legacy 'hnsw'-
flavoured public name introduced as a compat shim in steps 1-5. The
algorithm-neutral surface is now the only surface.

REMOVED — PHASE A (type aliases)

src/plugin.ts
- Removed `export type HnswProvider = VectorIndexProvider` alias.
- Removed `export type DiskAnnProvider = VectorIndexProvider` alias.

src/index.ts
- Removed `export const HNSWIndex = JsHnswVectorIndex` alias.

src/types/brainy.types.ts
- Removed `BrainyStats.indexHealth.hnsw` field (the new `vector` field
  carries the same boolean).

src/brainy.ts
- `stats()` no longer emits the legacy `hnsw` field on `indexHealth`.

REMOVED — PHASE B (storage adapter rename, 8 adapters)

Repo-wide rename: `saveHNSWData` → `saveVectorIndexData` and
`getHNSWData` → `getVectorIndexData` across:

- src/storage/adapters/baseStorageAdapter.ts (abstract declarations)
- src/storage/adapters/fileSystemStorage.ts
- src/storage/adapters/gcsStorage.ts
- src/storage/adapters/r2Storage.ts
- src/storage/adapters/s3CompatibleStorage.ts
- src/storage/adapters/azureBlobStorage.ts
- src/storage/adapters/opfsStorage.ts
- src/storage/adapters/memoryStorage.ts
- src/storage/adapters/historicalStorageAdapter.ts
- src/brainy.ts (call sites)
- src/hnsw/hnswIndex.ts + src/hnsw/typeAwareHNSWIndex.ts (call sites)

The default-delegation wrappers added in scaffold step 4 are removed
(would have been duplicate declarations after the rename).

REMOVED — PHASE C (cache category 'hnsw')

src/utils/unifiedCache.ts
- Cache-category union narrowed from
    'hnsw' | 'vectors' | 'metadata' | 'embedding' | 'other'
  to
    'vectors' | 'metadata' | 'embedding' | 'other'
- typeAccessCounts, typeSizes, typeCounts, accessRatios, sizeRatios,
  and the fairness-check iterator all drop the 'hnsw' key.
- Per planning § 2.5: pre-8.0 'hnsw' cache entries are an in-memory
  category. Cache is rebuildable; entries naturally don't exist after
  a restart, so no migration path is needed.

src/hnsw/hnswIndex.ts
- 3 cache.set() call sites migrated from category 'hnsw' to 'vectors'.
- Cache key prefix `hnsw:vector:` → `vector:`.
- typeCounts/typeSizes/typeAccessCounts accessor renames
  `.hnsw` → `.vectors`.

tests/unit/utils/unifiedCache-eviction.test.ts
- Test fixtures updated: cache.set(..., 'hnsw', ...) → cache.set(..., 'vectors', ...).
- Stats assertion `stats.typeSizes.hnsw` → `stats.typeSizes.vectors`.

REMOVED — PHASE D (config.hnsw)

src/types/brainy.types.ts
- Removed `BrainyConfig.hnsw` field entirely. The 8.0 surface is
  `BrainyConfig.vector.{recall, quantization, vectorStorage, advanced}`.

src/brainy.ts
- normalizeConfig() no longer emits a `hnsw` field on Required<BrainyConfig>.
- setupIndex() rewired:
  - Reads from `this.config.vector` (not `this.config.hnsw`).
  - Calls `resolveJsHnswConfig(this.config.vector)` to translate the
    `recall` preset into M / efConstruction / efSearch knobs (with
    `advanced.hnsw` overrides winning when supplied).
- Imports `resolveJsHnswConfig` from './utils/recallPreset.js'.

NOT IN THIS COMMIT (deliberately)

- Persisted file path migration `_system/hnsw-*.json` →
  `_system/vector-index-*.json`. Requires dual-read logic on boot
  across 8 storage adapters. Per integration doc lines 531-539:
  "Reader accepts either spelling on load; writer emits the new spelling
  only; brains self-migrate on the next persist after upgrade." This is
  a separate body of work and lands in a follow-up commit before 8.0 GA.
- `config.hnswPersistMode` top-level field is unchanged. It's not in
  the rename inventory; a future commit can fold it into
  `config.vector.persistMode` if desired.
- strictConfig enforcement wiring. The field is accepted by
  normalizeConfig() with default 'warn'; the actual warning emission at
  knob-mismatch sites lands when the config-resolution layer is touched
  for the persisted-path migration.

VERIFICATION

- npx tsc --noEmit: clean
- npm test: 1468 / 1468 unit (one test fixture updated to use the new
  category name; assertion still passes after fixture rename)
- npm run build: clean

The 8.0 PR's user-facing surface is now algorithm-neutral end-to-end:
VectorIndexProvider, config.vector.recall, JsHnswVectorIndex,
saveVectorIndexData, 'vectors' cache category, indexHealth.vector,
strictConfig — all standalone. No legacy 'hnsw' name remains in any
public type or method signature.

src/storage/adapters/azureBlobStorage.ts

@@ -1768,7 +1768,7 @@ export class AzureBlobStorage extends BaseStorage {
    * Uses BaseStorage's getNoun/saveNoun (type-first paths)
    * CRITICAL: Uses mutex locking to prevent read-modify-write races
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -1829,7 +1829,7 @@ export class AzureBlobStorage extends BaseStorage {
    * Get HNSW graph data for a noun
    * Uses BaseStorage's getNoun (type-first paths)
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/baseStorageAdapter.ts

@@ -95,49 +95,24 @@ export abstract class BaseStorageAdapter implements StorageAdapter {
 
   abstract getVerbMetadata(id: string): Promise<any | null>
 
-  // Vector Index Persistence (Brainy 8.0 — algorithm-neutral surface)
-  // The legacy `saveHNSWData` / `getHNSWData` names persist as default-method
-  // aliases so existing implementations continue to work mid-migration; the
-  // 8.0 final cleanup commit removes the old names.
+  // Vector Index Persistence (Brainy 8.0 — algorithm-neutral surface).
+  // Concrete adapters persist the per-entity HNSW graph node (level + connections)
+  // under these methods. Cortex's DiskANN-style native vector index doesn't use
+  // them (it persists its own single mmap'd `.dkann` file under
+  // `_system/vector-index/<shard>.dkann` per BRAINY-8.0-RENAME-COORDINATION § B.2).
 
   abstract getNounVector(id: string): Promise<number[] | null>
 
-  abstract saveHNSWData(nounId: string, hnswData: {
+  abstract saveVectorIndexData(nounId: string, data: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void>
 
-  abstract getHNSWData(nounId: string): Promise<{
+  abstract getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null>
 
-  /**
-   * Persist vector-index graph state for an entity (Brainy 8.0 name).
-   * Default implementation delegates to {@link saveHNSWData}; concrete
-   * adapters may override directly. The final 8.0 cleanup removes the
-   * legacy `saveHNSWData` name.
-   */
-  async saveVectorIndexData(nounId: string, data: {
-    level: number
-    connections: Record<string, string[]>
-  }): Promise<void> {
-    return this.saveHNSWData(nounId, data)
-  }
-
-  /**
-   * Read vector-index graph state for an entity (Brainy 8.0 name).
-   * Default implementation delegates to {@link getHNSWData}; concrete
-   * adapters may override directly. The final 8.0 cleanup removes the
-   * legacy `getHNSWData` name.
-   */
-  async getVectorIndexData(nounId: string): Promise<{
-    level: number
-    connections: Record<string, string[]>
-  } | null> {
-    return this.getHNSWData(nounId)
-  }
-
   abstract saveHNSWSystem(systemData: {
     entryPointId: string | null
     maxLevel: number

src/storage/adapters/fileSystemStorage.ts

@@ -2810,7 +2810,7 @@ export class FileSystemStorage extends BaseStorage {
    * Uses BaseStorage's getNoun/saveNoun (type-first paths)
    * CRITICAL: Preserves mutex locking to prevent read-modify-write races
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -2871,7 +2871,7 @@ export class FileSystemStorage extends BaseStorage {
    * Get HNSW graph data for a noun
    * Uses BaseStorage's getNoun (type-first paths)
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/gcsStorage.ts

@@ -1736,7 +1736,7 @@ export class GcsStorage extends BaseStorage {
    * Uses BaseStorage's getNoun/saveNoun (type-first paths)
    * CRITICAL: Uses mutex locking to prevent read-modify-write races
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -1797,7 +1797,7 @@ export class GcsStorage extends BaseStorage {
    * Get HNSW graph data for a noun
    * Uses BaseStorage's getNoun (type-first paths)
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/historicalStorageAdapter.ts

@@ -462,7 +462,7 @@ export class HistoricalStorageAdapter extends BaseStorage {
   /**
    * WRITE BLOCKED: Historical storage is read-only
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -492,7 +492,7 @@ export class HistoricalStorageAdapter extends BaseStorage {
   /**
    * Get HNSW data from historical state
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/memoryStorage.ts

@@ -415,7 +415,7 @@ export class MemoryStorage extends BaseStorage {
    * Even in-memory operations can race due to async/await interleaving
    * Prevents data corruption when multiple entities connect to same neighbor simultaneously
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -458,7 +458,7 @@ export class MemoryStorage extends BaseStorage {
   /**
    * Get HNSW graph data for a noun
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/opfsStorage.ts

@@ -1453,7 +1453,7 @@ export class OPFSStorage extends BaseStorage {
    * Uses BaseStorage's getNoun/saveNoun (type-first paths)
    * CRITICAL: Preserves mutex locking to prevent read-modify-write races
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -1503,7 +1503,7 @@ export class OPFSStorage extends BaseStorage {
    * Get HNSW graph data for a noun
    * Uses BaseStorage's getNoun (type-first paths)
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/r2Storage.ts

@@ -1090,7 +1090,7 @@ export class R2Storage extends BaseStorage {
     return noun ? noun.vector : null
   }
 
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -1130,7 +1130,7 @@ export class R2Storage extends BaseStorage {
     }
   }
 
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {

src/storage/adapters/s3CompatibleStorage.ts

@@ -3723,7 +3723,7 @@ export class S3CompatibleStorage extends BaseStorage {
    * Uses BaseStorage's getNoun/saveNoun (type-first paths)
    * CRITICAL: Uses mutex locking to prevent read-modify-write races
    */
-  public async saveHNSWData(nounId: string, hnswData: {
+  public async saveVectorIndexData(nounId: string, hnswData: {
     level: number
     connections: Record<string, string[]>
   }): Promise<void> {
@@ -3784,7 +3784,7 @@ export class S3CompatibleStorage extends BaseStorage {
    * Get HNSW graph data for a noun
    * Uses BaseStorage's getNoun (type-first paths)
    */
-  public async getHNSWData(nounId: string): Promise<{
+  public async getVectorIndexData(nounId: string): Promise<{
     level: number
     connections: Record<string, string[]>
   } | null> {