feat: enable document orientation detection for scanned PDFs

- Enable PP-StructureV3's use_doc_orientation_classify feature
- Detect rotation angle from doc_preprocessor_res.angle
- Swap page dimensions (width <-> height) for 90°/270° rotations
- Output PDF now correctly displays landscape-scanned content

Also includes:
- Archive completed openspec proposals
- Add simplify-frontend-ocr-config proposal (pending)
- Code cleanup and frontend simplification

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/UploadPage.tsx

@@ -15,7 +15,7 @@ export default function UploadPage() {
   const navigate = useNavigate()
   const { toast } = useToast()
   const [selectedFiles, setSelectedFiles] = useState<File[]>([])
-  const { setBatchId, setFiles, setUploadProgress } = useUploadStore()
+  const { setBatchId, setUploadProgress } = useUploadStore()
 
   const uploadMutation = useMutation({
     mutationFn: async (files: File[]) => {
@@ -28,10 +28,10 @@ export default function UploadPage() {
       return tasks
     },
     onSuccess: (tasks) => {
-      // For now, just use the first task_id as batch_id
-      // TODO: Update store to handle multiple tasks
+      // Use the first task_id as the current batch identifier
+      // Note: Type assertion needed - store expects number but API returns string UUID
       if (tasks.length > 0) {
-        setBatchId(tasks[0].task_id as any)  // temporary workaround
+        setBatchId(tasks[0].task_id as unknown as number)
       }
       toast({
         title: t('upload.uploadSuccess'),