Adds the web gateway layer for DB-backed user management (#1605):
Auth refactor:
- CombinedAuthState wraps env-var tokens (MultiAuthState) + optional
DbAuthenticator for DB-backed token lookup with LRU cache (60s TTL,
1024 max entries)
- auth_middleware tries env-var tokens first, then DB fallback
- From<MultiAuthState> impl for backward compatibility
- main.rs wires with_db_auth when database is available
API handlers (12 new endpoints):
- /api/admin/users — CRUD: create, list, detail, update, suspend, activate
- /api/tokens — create (returns plaintext once), list, revoke
- /api/invitations — create, list, accept (creates user + first token)
Token creation: 32 random bytes → hex plaintext, SHA-256 hash stored.
Invitation accept: validates hash + pending + not expired, creates
user record and first API token atomically.
All test files updated for CombinedAuthState type change.
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
