feat(8.0): API simplification — remove neural()/Db.search, one storage path key, integration→0

8.0 RC cleanup toward "one place per thing, zero-config, no deprecation":

- Remove the `brain.neural()` clustering namespace (ImprovedNeuralAPI + the dead
  legacy NeuralAPI + the neural CLI + neural-only types). Similarity is `find({vector})`
  / `similar({to})`; attribute grouping is the aggregation `GROUP BY` engine. The separate
  entity-extraction / smart-import feature (NeuralImport, NeuralEntityExtractor, SmartExtractor,
  NaturalLanguageProcessor, `brain.extract()`/`brain.nlp()`) is kept.
- Remove `Db.search()`; `find()` is the one query verb (accepts a bare string or FindParams).
  Fix the bundled MCP client, which called a non-existent `brain.search(query, limit)` →
  now `find({ query, limit })`.
- Storage config: collapse to one canonical top-level `path` key. The pre-8.0 aliases
  (`rootDirectory`, `options.*`, `fileSystemStorage.*`) are removed and now THROW with the
  exact rename instead of silently defaulting to `./brainy-data` on upgrade. A single resolver
  feeds createStorage, the 7.x→8.0 migration probe, and the plugin-factory handoff, so a native
  storage provider resolves the identical root (no split-brain).
- Fix `similar({ threshold })`: the min-similarity filter was silently dropped; it is now
  applied as a post-filter on `result.score` (the documented way to bound semantic results).
- Fix `vfs.rename()` on a directory: child path updates spread the entity vector into `update()`
  and failed dimension validation; they are metadata-only updates now.
- Fix `vfs.move()`: copy+delete orphaned the content-addressed content blob (the destination
  shared the source hash, then unlink removed it). `move()` now delegates to `rename()` — an
  in-place path change that preserves the blob and the entity id, for files and directories.
- Fix streaming import: the bulk fast path never flushed mid-import nor signalled queryability.
  Entity writes are now chunked by a progressive flush interval (100 → 1000 → 5000); each chunk
  flushes and emits `progress.queryable`, so imported data is queryable during the import.
- Sweep all docs, comments, and JSDoc for the removed/changed APIs.

Integration suite: 49 files / 588 passed / 0 failed. Unit: 80 files / 1456 passed, no type errors.

src/db/db.ts

@@ -407,33 +407,6 @@ export class Db<T = any> {
     }
   }
 
-  /**
-   * @description Semantic (vector) search **as of this view's generation** —
-   * convenience for `find({ query, ...options })`. At the current generation
-   * the live vector index serves it directly; at a historical generation the
-   * at-generation index materialization serves it (built lazily on first
-   * use — O(n at G) once per `Db`, freed on release; see the module doc).
-   * Speculative overlays throw {@link SpeculativeOverlayError}: overlay
-   * entities carry no embeddings, so the result would silently exclude them.
-   *
-   * @param query - Natural-language search query.
-   * @param options - Additional `FindParams` (limit, filters, …).
-   * @returns Semantic search results as of this generation.
-   * @throws SpeculativeOverlayError on speculative `with()` overlays.
-   */
-  async search(query: string, options?: Omit<FindParams<T>, 'query'>): Promise<Result<T>[]> {
-    this.assertUsable('search')
-
-    if (this.overlay) {
-      throw new SpeculativeOverlayError('vector search', this.gen)
-    }
-    if (!this.isHistorical()) {
-      return this.host.find({ ...(options ?? {}), query })
-    }
-    const materialized = await this.materialize()
-    return materialized.find({ ...(options ?? {}), query })
-  }
-
   /**
    * @description Serialize part or all of this database value into a portable
    * `PortableGraph` document, read **as of this view's generation**. Because `export`

src/db/errors.ts

@@ -97,7 +97,7 @@ export class GenerationConflictError extends Error {
  * @example
  * const spec = await brain.now().with([{ op: 'add', type, data: 'draft' }])
  * await spec.find({ where: { draft: true } })  // ✅ metadata find — supported
- * await spec.search('semantic query')          // ❌ throws this error
+ * await spec.find({ query: 'semantic query' }) // ❌ throws this error
  * await brain.transact([{ op: 'add', type, data: 'draft' }]) // → full surface
  */
 export class SpeculativeOverlayError extends Error {