Remove REST API, keep GraphQL as sole API

- Add missing GraphQL mutations: retryJob, updateAsset, deleteAsset
- Add UpdateAssetRequest and DeleteResult to schema source of truth
- Move Lambda callback endpoint to main.py (only REST endpoint)
- Remove REST routes, pydantic schemas, and deps
- Remove pydantic target from modelgen.json
- Update architecture diagrams and documentation

schema/models/api.py

@@ -40,4 +40,19 @@ class ScanResult:
     files: List[str] = field(default_factory=list)
 
 
+@dataclass
+class UpdateAssetRequest:
+    """Request body for updating asset metadata."""
+
+    comments: Optional[str] = None
+    tags: Optional[List[str]] = None
+
+
+@dataclass
+class DeleteResult:
+    """Result of a delete operation."""
+
+    ok: bool = False
+
+
 # Note: WorkerStatus is defined in grpc.py and reused here