feat: add maintenance system with index reconciliation

Complete maintenance subsystem for index health and cleanup:

Endpoints:
- GET /maintenance/health - lightweight (or detailed) health check
- POST /maintenance/cleanup/all - full orphan cleanup
- POST /maintenance/cleanup/vectors - purge orphan vector chunks
- POST /maintenance/cleanup/graph - purge orphan graph nodes
- POST /maintenance/reconcile-index - cleanup + reindex missing pages

Bidirectional orphan detection:
- find_documents_without_vectors() in GraphService
- find_chunks_without_graph_nodes() in VectorService

Redis integration:
- Tracks last_cleanup timestamp for scheduler visibility

Config additions:
- Document store, volatile cache, and maintenance settings
- VectorServiceDep and GraphServiceDep type aliases

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.py

@@ -50,7 +50,8 @@ app.add_middleware(
 # Register routers
 from src.routers import (
     wiki, tools, graph, vector, hybrid_rag, consolidation,
-    ingestion, entity_linking, webhooks, rag_search, content
+    ingestion, entity_linking, webhooks, rag_search, content,
+    maintenance
 )
 
 app.include_router(wiki.router)
@@ -64,6 +65,7 @@ app.include_router(entity_linking.router)
 app.include_router(webhooks.router)
 app.include_router(rag_search.router)
 app.include_router(content.router)
+app.include_router(maintenance.router)
 
 # Mount static files directory for Wiki.js integration scripts
 static_dir = Path(__file__).parent.parent / "static"