fix: reorder notification DELETE routes so bulk clear matches first

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)

apps/api/src/services/lifecycle_hooks.py

@@ -139,11 +139,7 @@ async def publish_lifecycle_event(
     if not _should_notify(event_type, effective_status):
         return
 
-    severity = (
-        "error"
-        if event_type == "instance.error"
-        else "success"
-    )
+    severity = "error" if event_type == "instance.error" else "success"
     title = _derive_title(event_type)
 
     try: