fix(vidmoly): correct multipart fields & JSON response shape

Captured the real browser upload POST and compared to our request.
Two corrections:

  - The file field is named 'file', not 'file_0'. The XFS-indexed
    naming was a bad guess — the current transit accepts only 'file'.
  - The form also needs 'to_json=1' (forces JSON response instead of
    an HTML redirect page, matching what the browser submits) and
    'fld_id=0' (destination folder, 0 = root). Dropped upload_type,
    srv_tmp_url, utype — those were XFS remnants and aren't part of
    the current server's contract.
  - Response shape is now { status: 'OK', file_code, msg } instead of
    the older { files: [...] } / { result: ... } XFS variants; the
    parser handles all three plus carries the server's msg forward
    on explicit rejections.

lib/vidmoly-upload.js

@@ -141,9 +141,10 @@ class VidmolyUploader {
     }
     return {
       uploadUrl: payload.upload_url,
-      // Classic XFS upload fields in the order the server expects.
-      params: { upload_type: 'file', sess_id: payload.sess_id, srv_tmp_url: '', utype: 'reg' },
-      fileFieldName: 'file_0'
+      // Fields verified from a real browser POST capture.
+      // to_json=1 forces a JSON response instead of an HTML redirect page.
+      params: { sess_id: payload.sess_id, to_json: '1', fld_id: '0' },
+      fileFieldName: 'file'
     };
   }
 
@@ -244,28 +245,33 @@ class VidmolyUploader {
       resultHtml = await body.text();
     }
 
-    // Try JSON first (some XFS versions return JSON)
+    // Try JSON first. The current transit server returns
+    // { status: "OK", file_code: "...", msg: "Upload Completed" }.
+    // Legacy XFS shapes (json.files / json.result) are kept as fallback.
     try {
       const json = JSON.parse(resultHtml);
+      if (json.status && /ok/i.test(json.status) && json.file_code) {
+        return this._buildUrlsFromCode(json.file_code);
+      }
+      if (json.file_code || json.filecode) {
+        return this._buildUrlsFromCode(json.file_code || json.filecode);
+      }
       if (json.files && json.files.length > 0) {
         const f = json.files[0];
-        const code = f.filecode || f.file_code;
-        return {
-          download_url: code ? `${BASE_URL}/w/${code}` : null,
-          embed_url: code ? `${BASE_URL}/embed-${code}.html` : null,
-          file_code: code
-        };
+        return this._buildUrlsFromCode(f.filecode || f.file_code);
       }
       if (json.result) {
         const r = Array.isArray(json.result) ? json.result[0] : json.result;
         const code = r.filecode || r.file_code;
-        return {
-          download_url: r.download_url || (code ? `${BASE_URL}/w/${code}` : null),
-          embed_url: r.embed_url || (code ? `${BASE_URL}/embed-${code}.html` : null),
-          file_code: code
-        };
+        const urls = this._buildUrlsFromCode(code);
+        if (urls) return urls;
       }
-    } catch {}
+      if (json.status && !/ok/i.test(json.status) && json.msg) {
+        throw new Error(`Vidmoly Upload abgelehnt: ${json.msg}`);
+      }
+    } catch (err) {
+      if (err && /Vidmoly Upload abgelehnt/.test(err.message)) throw err;
+    }
 
     try {
       return this._parseUploadResult(resultHtml);