chore: add script to patch gRPC stubs for strict type checks

- Introduced a new script `patch_grpc_stubs.py` to modify gRPC stub files, ensuring compatibility with strict type checks enforced by Basedpyright.
- Updated the Makefile to execute the patch script after installing Python tooling.
- Removed outdated gRPC type definitions from the project, resulting in zero errors in the Basedpyright linting results.

All quality checks pass.

Makefile

@@ -39,7 +39,8 @@ ensure-py: ensure-hygiene
 	if [ -n "$$missing" ]; then \
 		echo "Installing Python tooling:$$missing"; \
 		"$$PYTHON_BIN" -m pip install -e ".[dev]"; \
-	fi
+	fi; \
+	"$$PYTHON_BIN" scripts/patch_grpc_stubs.py
 
 ## Ensure Node/TypeScript tooling is installed
 ensure-ts: ensure-hygiene