refactor(8.0)!: remove distributed clustering subsystem — inert/orphaned, scale is single-process + native provider

The distributed-clustering subsystem never ran in production: it was inert,
orphaned dead code (faked consensus, stub replication, no live wiring, and it
did not interoperate with the 8.0 Db API). Brainy 8.0 is a single-process
library. Scale is single-process + the optional native provider
(@soulcraft/cortex, on-disk DiskANN to 10B+ vectors) + per-tenant pools +
horizontal read scaling (many reader processes, one writer).

Removed:
- src/distributed/ entirely (coordinator, shardManager, cacheSync,
  readWriteSeparation, queryPlanner, healthMonitor, configManager,
  hashPartitioner, shardMigration, domainDetector, storageDiscovery, http/network
  transports). ReaderMode/HybridMode relocated to src/storage/operationalModes.ts
  (slimmed to the live surface).
- src/types/distributedTypes.ts; config.distributed field + JSDoc;
  coreTypes distributedConfig; memoryStorage distributedConfig persistence.
- DistributedRole enum + src/config/distributedPresets.ts and the orphaned
  src/config/extensibleConfig.ts (config/augmentation registry built on removed
  cloud adapters + distributed presets), plus their src/index.ts re-exports.
- 13 BRAINY_* cluster env vars; the storage setDistributedComponents hook;
  enableDistributedSearch (dead config flag); the metadata partition field;
  the distributed_ reserved key prefix.
- Orphaned src/storage/readOnlyOptimizations.ts (zero importers).
- Tests targeting the subsystem: distributed-demo, distributed-cluster helper,
  distributed-transactions, sharding-transactions.
- Docs: EXTENDING_STORAGE.md (deleted); scrubbed distributed/cluster/Raft/
  shard-manager/multi-node prose from v3-features, enterprise-for-everyone,
  augmentations-actual, complete-feature-list, vfs/README, vfs/ROADMAP,
  vfs/VFS_CORE, capacity-planning, transactions, MIGRATION-V3-TO-V4,
  storage-architecture; reframed scale prose to the 8.0 model.

Kept: src/storage/sharding.ts (local-disk 256-bucket directory sharding via
getShardIdFromUuid — used live by baseStorage, unrelated to clustering);
the multi-process mode: 'reader' | 'writer' roles; semantic/HNSW clustering.

RELEASES.md: added a removed-surfaces row documenting the cut and the 8.0
scale model.

src/index.ts

@@ -77,32 +77,9 @@ export type {
 // Export Aggregation Engine
 export { AggregationIndex, AggregateMaterializer, bucketTimestamp, parseBucketRange } from './aggregation/index.js'
 
-// Export zero-configuration types and enums
+// Export zero-configuration input type
 export {
-  // Preset names
-  PresetName,
-  // Model configuration
-  ModelPrecision,
-  // Storage configuration  
-  StorageOption,
-  // Feature configuration
-  FeatureSet,
-  // Distributed roles
-  DistributedRole,
-  // Categories
-  PresetCategory,
-  // Config type
-  BrainyZeroConfig,
-  // Extensibility
-  StorageProvider,
-  registerStorageAugmentation,
-  registerPresetAugmentation,
-  // Preset utilities
-  getPreset,
-  isValidPreset,
-  getPresetsByCategory,
-  getAllPresetNames,
-  getPresetDescription
+  BrainyZeroConfig
 } from './config/index.js'
 
 // Export Neural Import (AI data understanding)