P0: When bge-embed/IPC recall fails, fall back to graph.db keyword search (FallbackTextSearch) instead of 500 error. Response includes X-Fallback: graph header.
P2: Add trust_score, retrieval_count, helpful_count columns to graph_edges table. New POST /api/v1/graph/edge/feedback endpoint. UpdateEdgeTrustScores batch calculation.
- NewCachedGraphStore: governance.GraphStore wrapper, only Navigate() is cached
- GraphCacheRef: expose InvalidateAll() + Stats() for cache management
- Cache invalidation on graph/edge add, graph/cleanup (non-dry-run)
- New /api/v1/cache/stats endpoint for cache monitoring
- /api/v1/health now registered at /api/v1/health path too
- normalizeEntity: preserve Unicode letters (Chinese chars not stripped)