fix(storage): v4.8.0 metadata architecture refactoring - FIXES VFS bug

CRITICAL FIX: VFS bug that persisted through v4.5.1-v4.7.4 is NOW FIXED.

Root Cause:
- Storage adapters were not properly extracting standard fields from metadata
- This caused getVerbsBySource_internal() to return 0 relationships despite relationships existing
- VFS PathResolver couldn't navigate directory structure

Solution - Metadata Architecture Refactoring:
1. Move standard fields to top-level of HNSWNounWithMetadata and HNSWVerbWithMetadata
   - type, createdAt, updatedAt, confidence, weight, service, data, createdBy
2. Update all 9 storage adapters to extract standard fields from metadata on load
3. Maintain backward compatibility at storage layer (metadata files unchanged)

Changes:
- src/coreTypes.ts: Update HNSWNounWithMetadata and HNSWVerbWithMetadata interfaces
  - Add top-level standard fields
  - Change data type from unknown to Record<string, any>
  - Add confidence field to GraphVerb
- src/storage/baseStorage.ts: Add type cast pattern for standard field extraction
- src/storage/adapters/*.ts: Fix all 9 adapters (memoryStorage, fileSystemStorage, gcsStorage,
  s3CompatibleStorage, r2Storage, opfsStorage, azureBlobStorage, typeAwareStorageAdapter)
  - Extract standard fields from metadata on load
  - Place at top-level of returned entities
- src/api/DataAPI.ts: Read fields from top-level instead of metadata
- src/graph/graphAdjacencyIndex.ts: Convert HNSWVerbWithMetadata to GraphVerb format
- src/utils/metadataIndex.ts: Fix typo (metadata → entityOrMetadata)
- src/types/brainy.types.ts: Add createdBy field to AddParams
- src/types/graphTypes.ts: Add service field to GraphVerb

Test Results:
✅ VFS bug FIXED - vfs.readdir('/') now returns files (was returning empty array)
✅ getVerbsBySource_internal() now returns relationships correctly
✅ Build succeeds with ZERO compilation errors
✅ 95.7% of tests pass (954/997)

Breaking Changes:
- None - backward compatibility maintained at storage layer

Version: 4.8.0

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/api/DataAPI.ts

@@ -103,9 +103,9 @@ export class DataAPI {
       const entity = {
         id: noun.id,
         vector: includeVectors ? noun.vector : undefined,
-        type: noun.metadata?.noun || NounType.Thing,
+        type: noun.type || NounType.Thing, // v4.8.0: type at top-level
         metadata: noun.metadata,
-        service: noun.metadata?.service
+        service: noun.service // v4.8.0: service at top-level
       }
       entities.push(entity)
     }
@@ -122,7 +122,7 @@ export class DataAPI {
         from: verb.sourceId,
         to: verb.targetId,
         type: verb.verb as string,
-        weight: verb.metadata?.weight || 1.0,
+        weight: verb.weight || 1.0, // v4.8.0: weight at top-level
         metadata: verb.metadata
       })
     }