Tighten prompt_template_source.notes: explicit 5-tier classification per 2026-06-01 priority rules

metadata.json

@@ -37,7 +37,7 @@
       "prompt_template_source": {
         "origin": "official",
         "reference": "https://github.com/open-compass/VLMEvalKit/blob/main/vlmeval/dataset/image_caption.py (ImageCaptionDataset canonical caption prompt)",
-        "notes": "VLMEvalKit ImageCaptionDataset canonical Flickr8k captioning prompt."
+        "notes": "Tier 3: VLMEvalKit ImageCaptionDataset canonical Flickr8k captioning prompt."
       }
     }
   }