fix(terminal): avoid lazy-loading tool manifest in async websocket handler

The container-user resolver introduced in 9f72093 accessed
'tool_type.manifest', which triggers a SQLAlchemy lazy load inside the
async WebSocket coroutine and raises MissingGreenlet. Fetch the manifest
explicitly with db_session.get() instead, matching the pattern used in
instance_service.py.

- Replace relationship access with explicit async loads in
  _resolve_container_user().
- Add unit tests covering manifest, base-definition, legacy, and missing
  manifest cases.
- Update project map artifacts.

Quality gates: pytest tests/api tests/services/test_terminal_manager_multi.py tests/unit (247 passed), ruff check (clean).

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

@@ -2,17 +2,23 @@
 dir: apps/api/src
 
 ## role
-Core FastAPI web application package that bootstraps and configures the Headquarter API service with database, authentication, logging, and modular routing infrastructure.
+Core FastAPI application package that initializes and configures the Headquarter API with database, authentication, logging, and middleware infrastructure.
 ## parent
 index: apps/api/.pi-map.index.md
 map: apps/api/.pi-map.md
 ## children
+- apps/api/src/.ruff_cache
+  index: apps/api/src/.ruff_cache/.pi-map.index.md
+  map: apps/api/src/.ruff_cache/.pi-map.md
 - apps/api/src/api
   index: apps/api/src/api/.pi-map.index.md
   map: apps/api/src/api/.pi-map.md
 - apps/api/src/auth
   index: apps/api/src/auth/.pi-map.index.md
   map: apps/api/src/auth/.pi-map.md
+- apps/api/src/headquarter_api.egg-info
+  index: apps/api/src/headquarter_api.egg-info/.pi-map.index.md
+  map: apps/api/src/headquarter_api.egg-info/.pi-map.md
 - apps/api/src/models
   index: apps/api/src/models/.pi-map.index.md
   map: apps/api/src/models/.pi-map.md
@@ -46,6 +52,6 @@ map: apps/api/src/.pi-map.md
 - change src config
   read: config.py, logging_config.py
 - explore src subdirectories
-  index: apps/api/src/api/.pi-map.index.md, apps/api/src/auth/.pi-map.index.md, apps/api/src/models/.pi-map.index.md
+  index: apps/api/src/.ruff_cache/.pi-map.index.md, apps/api/src/api/.pi-map.index.md, apps/api/src/auth/.pi-map.index.md
 ## dirty
 -