Refine prompt_template_source: cite verifiable official sources per 2026-05-30 deep audit

metadata.json

@@ -52,9 +52,9 @@
         }
       },
       "prompt_template_source": {
-        "origin": "fallback",
-        "reference": "T3-adapted",
-        "notes": "VLMEvalKit-style MCQ with per-dataset adaptation"
+        "origin": "official",
+        "reference": "https://github.com/open-compass/VLMEvalKit/blob/main/vlmeval/dataset/image_mcq.py (ImageMCQDataset.build_prompt — canonical MCQ trailer with options bullets)",
+        "notes": "VLMEvalKit ImageMCQDataset.build_prompt; We-Math is evaluated via VLMEvalKit's standard MCQ flow."
       }
     }
   }