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/tools/keys.py

@@ -114,10 +114,14 @@ def register_keys_tool(mcp: FastMCP) -> None:
                 if permissions is not None:
                     input_data["permissions"] = permissions
                 data = await make_graphql_request(MUTATIONS["create"], {"input": input_data})
-                return {
-                    "success": True,
-                    "key": (data.get("apiKey") or {}).get("create", {}),
-                }
+                created_key = (data.get("apiKey") or {}).get("create")
+                if not created_key:
+                    return {
+                        "success": False,
+                        "key": {},
+                        "message": "API key creation failed: no data returned from server",
+                    }
+                return {"success": True, "key": created_key}
 
             if action == "update":
                 if not key_id:
@@ -128,10 +132,14 @@ def register_keys_tool(mcp: FastMCP) -> None:
                 if roles is not None:
                     input_data["roles"] = roles
                 data = await make_graphql_request(MUTATIONS["update"], {"input": input_data})
-                return {
-                    "success": True,
-                    "key": (data.get("apiKey") or {}).get("update", {}),
-                }
+                updated_key = (data.get("apiKey") or {}).get("update")
+                if not updated_key:
+                    return {
+                        "success": False,
+                        "key": {},
+                        "message": "API key update failed: no data returned from server",
+                    }
+                return {"success": True, "key": updated_key}
 
             if action == "delete":
                 if not key_id: