feat(auth): add admin user management dashboard

- Add UserProfile model (app/models.py) with per-user settings: display_name, daily_upload_limit, notes, is_blocked
- Add Alembic migration 013_add_user_profiles for the new table
- Add REST API at /api/admin/users/ with list, get, upsert (PUT), delete endpoints (admin-only)
- Add HTML template admin_users.html with Alpine.js: filterable user list, paginated table, edit/create modal, delete confirmation modal
- Add view handler at /admin/users (admin-only redirect guard)
- Register routers in app/api/__init__.py and app/views/__init__.py
- Add 'Users' link to admin nav dropdown in base.html (desktop + mobile)
- Add 27 tests covering auth, list, get, upsert, delete, and model constraints
- Register UserProfile in conftest.py model imports
- Document new endpoints in docs/API.md

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/conftest.py

@@ -59,7 +59,14 @@ from app.database import Base  # noqa: E402
 from app.main import app as fastapi_app  # noqa: E402
 
 # Import models to register them with SQLAlchemy Base
-from app.models import DocumentMetadata, FileRecord, ProcessingLog, SavedSearch, WebhookConfig  # noqa: F401, E402
+from app.models import (  # noqa: F401, E402
+    DocumentMetadata,
+    FileRecord,
+    ProcessingLog,
+    SavedSearch,
+    UserProfile,
+    WebhookConfig,
+)
 
 
 @pytest.fixture(scope="session")