feat: add 5 notification mutations + comprehensive refactors from PR review

New notification actions (archive_many, create_unique, unarchive_many,
unarchive_all, recalculate) bring unraid_notifications to 14 actions.

Also includes continuation of CodeRabbit/PR review fixes:
- Remove redundant try-except in virtualization.py (silent failure fix)
- Add QueryCache protocol with get/put/invalidate_all to core/client.py
- Refactor subscriptions (manager, diagnostics, resources, utils)
- Update config (logging, settings) for improved structure
- Expand test coverage: http_layer, safety guards, schema validation
- Minor cleanups: array, docker, health, keys tools

Co-authored-by: Claude <noreply@anthropic.com>

unraid_mcp/main.py

@@ -11,12 +11,19 @@ import sys
 
 async def shutdown_cleanup() -> None:
     """Cleanup resources on server shutdown."""
+    try:
+        from .subscriptions.manager import subscription_manager
+
+        await subscription_manager.stop_all()
+    except Exception as e:
+        print(f"Error stopping subscriptions during cleanup: {e}", file=sys.stderr)
+
     try:
         from .core.client import close_http_client
 
         await close_http_client()
     except Exception as e:
-        print(f"Error during cleanup: {e}")
+        print(f"Error during cleanup: {e}", file=sys.stderr)
 
 
 def _run_shutdown_cleanup() -> None: