Strip MiMo's embedded model name from its artifacts (blind-Arena identity leak)

MiMo v2.5 Pro's one-shot outputs wrote the model name into the browser
title, an on-screen "Generated by MiMo v2.5 Pro" caption, a console log
(mythos-craft.html) and a watermark text at the bottom of the SVG
(pelican-cycling.svg), which would reveal its identity during blind
Arena voting. Removed those identity strings; generation logic untouched.
Documented the surgical fix in both run notes. MiMo was the only entry
with a visible model-name leak.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

outputs/xiaomi-mimo-v2-5-pro/pelican-cycling.svg

@@ -220,7 +220,4 @@
   <text x="400" y="50" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" font-weight="bold" fill="#1565C0" opacity="0.8">
     Pelican by the Sea
   </text>
-  <text x="400" y="75" text-anchor="middle" font-family="Arial, sans-serif" font-size="14" fill="#1976D2" opacity="0.6">
-    Generated by MiMo v2.5 Pro
-  </text>
 </svg>