fix: pi container repo mount target and npm update permissions

- Add Alembic migration to update built-in pi-agent manifest:
  * repo mount target from /workspace to ~/{{WORKSPACE_NAME}}
  * keep /workspace as compatibility symlink via working_dir
  * update startup chown target to $HOME/$WORKSPACE_NAME
- Pass REPO_NAME and WORKSPACE_NAME to compile_compose from instance_service
- Substitute {{WORKSPACE_NAME}} in manifest mount targets and expose it as
  a container env var so the entrypoint can create the /workspace symlink
- Generate entrypoint workspace symlink from runtime WORKSPACE_NAME env var
- Install npm_global packages into {home_dir}/.npm-global with PATH so the
  non-root container user can update global packages
- Update manifest compiler unit tests for the new behavior

Quality gates:
- pytest tests/unit: 207 passed
- ruff: clean on changed files
- mypy: clean on changed files
- alembic heads: single head

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

@@ -2,7 +2,7 @@
 dir: apps/api/src
 
 ## role
-Core application bootstrap and infrastructure layer for the Headquarter API, providing configuration, database connectivity, logging, and FastAPI application initialization.
+Core API application package for the "Headquarter API" providing configuration, database infrastructure, logging, and FastAPI application initialization.
 ## parent
 index: apps/api/.pi-map.index.md
 map: apps/api/.pi-map.md