fix: use repository name for workspace mount target

WORKSPACE_NAME was computed from os.path.basename(repo_path), so when a
workspace path ended in a directory like 'main', the container mount target
became /home/user/main instead of /home/user/{repo-name}.

- Use GitRepository.name for WORKSPACE_NAME/REPO_NAME in manifest and
  legacy dockerfile flows
- Add unit test verifying prepare_manifest_instance uses repo.name even
  when the workspace path basename differs

Quality gates:
- pytest tests/unit: 213 passed
- ruff: clean on changed files
- mypy: clean on changed files

apps/api/src/services/.pi-map.md

@@ -4,11 +4,11 @@ dir: apps/api/src/services
 index: apps/api/src/services/.pi-map.index.md
 
 ## role
-Marker package for the services layer in the API application
+Service layer for business logic encapsulation in the API application
 ## files
 - __init__.py | Empty file with no functionality
 ## arch
-Standard Python package structure using __init__.py for namespace declaration
+Minimal/placeholder package following Python package convention with empty __init__.py, awaiting future service module implementations
 ## tags
 init, empty, functionality
 ## symbols