fix: enable Render Changes button after AD VTT upload

adVttUploaded was missing from the hasChanges condition in
RerenderControls, leaving the button greyed out after an upload.
Pass the flag as a prop and include it in hasChanges; also show
an "Audio Description script was replaced" status message.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/RerenderControls.tsx

@@ -3,6 +3,7 @@ import { useState } from 'react';
 interface RerenderControlsProps {
   pendingRegenerations: number[];
   pausePointsModified: boolean;
+  adVttUploaded: boolean;
   isRendering: boolean;
   onRender: (options: { whisperRefine: boolean }) => void;
   onClearQueue: () => void;
@@ -11,13 +12,14 @@ interface RerenderControlsProps {
 export function RerenderControls({
   pendingRegenerations,
   pausePointsModified,
+  adVttUploaded,
   isRendering,
   onRender,
   onClearQueue,
 }: RerenderControlsProps) {
   const [whisperRefine, setWhisperRefine] = useState(false);
 
-  const hasChanges = pendingRegenerations.length > 0 || pausePointsModified;
+  const hasChanges = pendingRegenerations.length > 0 || pausePointsModified || adVttUploaded;
 
   return (
     <div className="bg-purple-50 border border-purple-200 rounded-lg p-4">
@@ -47,6 +49,12 @@ export function RerenderControls({
             </p>
           )}
 
+          {adVttUploaded && !pausePointsModified && pendingRegenerations.length === 0 && (
+            <p className="mt-1 text-sm text-purple-700">
+              Audio Description script was replaced
+            </p>
+          )}
+
           {!hasChanges && (
             <p className="mt-1 text-sm text-gray-500">
               No changes to render. Adjust pause points or queue TTS regenerations.

frontend/src/routes/admin/QCDetail.tsx

@@ -751,6 +751,7 @@ export function QCDetail() {
                       <RerenderControls
                         pendingRegenerations={pendingRegenerations}
                         pausePointsModified={pausePointsModified}
+                        adVttUploaded={adVttUploaded}
                         isRendering={isRendering}
                         onRender={handleRender}
                         onClearQueue={handleClearRegenerationQueue}