fix: enhance admin functionality and error handling in ingestion and analytics processes

feat: add Zustand stores for filters and UI state management

Use fresh Neo4j driver per request; create driver after Gemini extraction to avoid idle timeout

Add retry-on-SessionExpired for ingest writes; fix WebSocket driver init error handling

Fix defunct Neo4j connection: add keep-alive, liveness check, retry on SessionExpired

Fix startup imports and add graph_store module