## Summary
- sync an existing CWA-backed user's username when CWA renames it
- keep username collisions safe by assigning a stable `__cwa` alias
instead of overwriting a local account
- allow username updates through `UserDB` and cover
rename/collision/repeat-sync behavior
Fixes#1197.
## Testing
- `uv run ruff check shelfmark tests`
- `uv run ruff format --check shelfmark tests`
- `uv run vulture shelfmark`
- `uv run pytest tests/core/test_cwa_user_sync.py
tests/core/test_user_db.py tests/core/test_admin_users_api.py
tests/core/test_auth_api.py -k "cwa or update_user"` (36 passed)
- `uv run pytest tests/ -x --tb=short -m "not integration and not e2e"
--ignore=tests/config/test_entrypoint_permissions.py -q` (2445 passed, 5
skipped)
The entrypoint permission tests were excluded locally because macOS
ships Bash 3.2, which does not support the `${1,,}` expansion used by
`entrypoint.sh`; the same failure reproduces on an unchanged checkout.
`make python-typecheck` also currently reports the existing
`settings.py:147` callback return-type mismatch on the unchanged base.
Co-authored-by: CaliBrain <calibrain@l4n.xyz>
