FastAPI matches routes in declaration order. The DELETE /notifications
endpoint (bulk clear) was registered AFTER DELETE /notifications/{id},
so the path parameter route intercepted all requests to the bulk route,
causing a 422 UUID validation error instead of hitting clear_all.
Moved clear_all_notifications above dismiss_notification in the router.
Added regression test to verify route order.
Quality gates: pytest (22 passed)
Alex Blank
3d1f8d9cf7