Clear the stack update pill immediately after a manual/auto update (0.38.4)

The amber image-update indicator is fed from update_service._CACHE, which
only the background loop refreshed — after a per-stack Update/Pull the
stale digests kept the pill on until the next pass. Now the local digests
are reconciled with the cached remote digests right after a successful
pull/update (local backend, agent lifecycle, auto-update pass), and the
frontend invalidates the stack-updates queries after actions.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/services/update_service.py

@@ -269,6 +269,25 @@ async def stack_updates(stack_id: str, refresh: bool = True) -> dict:
     }
 
 
+def refresh_stack_local(stack_id: str) -> None:
+    """Re-read the local digests of one stack's images and reconcile them with
+    the cached remote digests (no registry calls). Called right after a manual
+    pull/update so the amber indicator clears immediately instead of lingering
+    until the next background pass."""
+    for image in stack_images(stack_id):
+        status = _CACHE.get(image)
+        if status is None:
+            continue
+        local = _local_digest(image)
+        status.current_digest = local
+        status.update_available = bool(
+            local and status.remote_digest and local != status.remote_digest
+        )
+        status.checked_at = time.time()
+        if not status.update_available:
+            _NOTIFIED.discard(image)
+
+
 async def check_all() -> dict[str, dict]:
     images = _all_running_images()
     for image in images: