fix SSE cleanup, filter add popover to completed only, derive isGenerating from pending set, handle not_found status

app/src/lib/hooks/useRestoreActiveTasks.tsx

@@ -15,7 +15,6 @@ const POLL_INTERVAL = 30000;
  */
 export function useRestoreActiveTasks() {
   const [activeDownloads, setActiveDownloads] = useState<ActiveDownloadTask[]>([]);
-  const setIsGenerating = useGenerationStore((state) => state.setIsGenerating);
   const setActiveGenerationId = useGenerationStore((state) => state.setActiveGenerationId);
   const addPendingGeneration = useGenerationStore((state) => state.addPendingGeneration);
 
@@ -26,18 +25,15 @@ export function useRestoreActiveTasks() {
     try {
       const tasks = await apiClient.getActiveTasks();
 
-      // Update generation state — restore pending generations (e.g., after page refresh)
+      // Restore pending generations (e.g., after page refresh)
       if (tasks.generations.length > 0) {
-        setIsGenerating(true);
         setActiveGenerationId(tasks.generations[0].task_id);
         for (const gen of tasks.generations) {
           addPendingGeneration(gen.task_id);
         }
       } else {
-        // Only clear if we were tracking a generation
         const currentId = useGenerationStore.getState().activeGenerationId;
         if (currentId) {
-          setIsGenerating(false);
           setActiveGenerationId(null);
         }
       }
@@ -63,7 +59,7 @@ export function useRestoreActiveTasks() {
       // Silently fail - server might be temporarily unavailable
       console.debug('Failed to fetch active tasks:', error);
     }
-  }, [setIsGenerating, setActiveGenerationId]);
+  }, [setActiveGenerationId, addPendingGeneration]);
 
   useEffect(() => {
     // Fetch immediately on mount