fix(controller): stop self-triggered reconcile loops

C2: updateLastSyncStatus wrote the sync-status annotation on every
successful reconcile. Because the source's watch predicate is the
'enabled' label (server-side filter), that Update fires a watch event
that re-enters Reconcile. With reconciled/error counts varying across
cycles, the value differs each time, so the API server bumps RV and
the loop never quiesces. Now skips the Update when the value matches
the existing annotation.

C3: NamespaceReconciler's happy-path returned RequeueAfter=3s
unconditionally. Every namespace in the cluster re-reconciled every
3 seconds forever, generating constant List calls per source kind.
Now returns ctrl.Result{}; cache-staleness windows are handled by
the manager's resync period and source freshness verification.

pkg/controller/source_reconciler.go

@@ -627,16 +627,24 @@ func (r *SourceReconciler) resolveTargetNamespaces(ctx context.Context, sourceOb
 	return targetNamespaces, nil
 }
 
-// updateLastSyncStatus updates the source resource's annotations with sync status.
+// updateLastSyncStatus updates the source resource's sync-status annotation.
+// Skips the Update call entirely if the value is unchanged; otherwise the
+// resulting watch event re-fires Reconcile and the controller spins on its
+// own writes. This is a no-op for steady-state convergence.
 func (r *SourceReconciler) updateLastSyncStatus(ctx context.Context, source runtime.Object, sourceObj metav1.Object, reconciledCount, errorCount int) error {
+	desired := fmt.Sprintf("reconciled:%d,errors:%d", reconciledCount, errorCount)
+
 	annotations := sourceObj.GetAnnotations()
+	if annotations[constants.AnnotationSyncStatus] == desired {
+		return nil
+	}
+
 	if annotations == nil {
 		annotations = make(map[string]string)
 	}
-
-	annotations[constants.AnnotationSyncStatus] = fmt.Sprintf("reconciled:%d,errors:%d", reconciledCount, errorCount)
-
+	annotations[constants.AnnotationSyncStatus] = desired
 	sourceObj.SetAnnotations(annotations)
+
 	// source (*unstructured.Unstructured) already implements client.Object
 	return r.Update(ctx, source.(*unstructured.Unstructured))
 }