fix(ai): keep the per-turn decimal in the response bar (mirrors onetime PR #86)

creditCost() used the same unary-+ pattern the dashboard did, so it carried the
same bug: 7.0 rendered as "7", and anything under 0.05 credits collapsed to "0" —
a run that cost something reading as free.

Fixed identically to AccountPage.tsx's rate(), with an explicit "<0.1" floor, so
the editor and the website format a cost the same way rather than drifting.

Verified: 23 suites, 0 failures; $0.0002 -> "<0.1", $0.70 -> "7.0", $0.46 -> "46".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ndemianc

extensions/levelcode-ai/media/chat.html

@@ -2433,7 +2433,11 @@
   function creditCost(micros){
     const c = toCredits(micros);
     if (c <= 0) { return '0'; }
-    return c < 10 ? String(+c.toFixed(1)) : Math.round(c).toLocaleString();
+    if (c >= 10) { return Math.round(c).toLocaleString(); }
+    // Fixed string, not +String(...): the unary + dropped the decimal (7.0 -> "7") and collapsed
+    // anything under 0.05 to "0" — a run that cost something reading as free. Same fix as the
+    // dashboard's rate(), kept identical so the two surfaces render a cost the same way.
+    return c < 0.05 ? '<0.1' : c.toFixed(1);
   }
 
   // Response action bar: (Retry) (Copy) (Helpful) (Unhelpful) … model · $cost · $left.