Add create_user method to LocalAuthProvider (bcrypt hash + INSERT,
raises ValueError on duplicate username/email).
Add UserService with 9 async methods: create/list/get/update/delete
(soft)/reset_password/assign_department/remove_department/list_user_departments. reset_password revokes all sessions via SessionService.
delete_user is soft (is_active=0, row preserved).
Add 9 user endpoints to routes/admin.py: POST/GET/PATCH/DELETE users,
reset-password, assign/remove department, list departments. All
guarded by _require_admin.
Tests: 40 unit + 37 integration = 77 new tests. Full admin suite
170 tests pass, no regressions.
chiguyong