Fix 404: use /gradio_api/upload path + gradio.FileData meta wrapper

The upload endpoint is under the /gradio_api/ prefix, not at the root.
Also wraps the file data in {meta: {_type: 'gradio.FileData'}} per the
Gradio 5.x REST API format that @gradio/client uses internally.

src/lib/services/scan.ts

@@ -17,7 +17,7 @@ export async function scanPhoto(image: File, hfToken: string): Promise<ScanResul
     // 1. Upload the image to Gradio's file upload endpoint
     const formData = new FormData();
     formData.append('files', image);
-    const uploadResp = await fetch(`${BACKEND_URL}/upload`, {
+    const uploadResp = await fetch(`${BACKEND_URL}/gradio_api/upload`, {
       method: 'POST',
       body: formData,
       credentials: 'omit',
@@ -36,7 +36,7 @@ export async function scanPhoto(image: File, hfToken: string): Promise<ScanResul
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({
         data: [
-          { path: filePath, orig_name: image.name, mime_type: image.type },
+          { path: filePath, orig_name: image.name, mime_type: image.type, meta: { _type: 'gradio.FileData' } },
           hfToken,
         ],
       }),