feat: v0.49 - Filter discovery API, remove deprecated methods, improve performance

BREAKING CHANGES:
- Removed deprecated getAllNouns() and getAllVerbs() methods
- All internal usage migrated to pagination-based methods

New Features:
- Filter Discovery API:
  - getFilterValues(field): Get all available values for a field
  - getFilterFields(): Get all filterable fields
  - Enables dynamic filter UI generation with O(1) field discovery
- Hybrid metadata indexing with field-level indexes
- Adaptive auto-flush for optimal performance
- LRU caching for metadata indexes

Improvements:
- Fixed ENAMETOOLONG errors from vector-based filenames
- Safe filename generation using hash-based approach
- Scalable chunked value storage for millions of entries
- Performance optimization with adaptive flush thresholds
- Added support for $includes operator in metadata filters

Technical:
- Replaced vector-based filenames with safe hash approach
- Implemented MetadataIndexCache with existing SearchCache pattern
- Field indexes enable O(1) filter discovery
- Adaptive flush based on performance metrics (20-200 entries)
- All tests passing with improved metadata filtering

src/storage/adapters/s3CompatibleStorage.ts

@@ -466,17 +466,6 @@ export class S3CompatibleStorage extends BaseStorage {
     }
   }
 
-  /**
-   * Get all nouns from storage (internal implementation)
-   */
-  protected async getAllNouns_internal(): Promise<HNSWNoun[]> {
-    // Use paginated method to avoid deprecation warning
-    const result = await this.getNodesWithPagination({
-      limit: 1000,
-      useCache: true
-    })
-    return result.nodes
-  }
 
   // Node cache to avoid redundant API calls
   private nodeCache = new Map<string, HNSWNode>()
@@ -854,15 +843,6 @@ export class S3CompatibleStorage extends BaseStorage {
     }
   }
 
-  /**
-   * Get all verbs from storage (internal implementation)
-   * @deprecated This method is deprecated and will be removed in a future version.
-   * It can cause memory issues with large datasets. Use getVerbsWithPagination() instead.
-   */
-  protected async getAllVerbs_internal(): Promise<HNSWVerb[]> {
-    this.logger.warn('getAllVerbs_internal() is deprecated and will be removed in a future version. Use getVerbsWithPagination() instead.')
-    return this.getAllEdges()
-  }
 
   /**
    * Get all edges from storage