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

metadata.json

@@ -53,7 +53,7 @@
       "prompt_template_source": {
         "origin": "official",
         "reference": "https://github.com/yfzhang114/MME-RealWorld README",
-        "notes": "byte-for-byte from cited source"
+        "notes": "Tier 1: byte-for-byte from cited source"
       }
     }
   }