fix: font sizes 21/25/17px, icon labels on send btn, no-wrap fix

- Sync preload script font sizes to match app.js (21/25/17px)
- Send button variants now show icons: ↑ Send, 📝 Note, ⚡ Run
- Remove fixed width on send-col; add white-space:nowrap + padding
  so "📝 Note" never wraps regardless of font size

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/static/style.css

@@ -626,7 +626,6 @@
             align-items: stretch;
             gap: 4px;
             flex-shrink: 0;
-            width: 80px;
         }
 
         /* Send button */
@@ -635,10 +634,11 @@
             border: 1px solid var(--user-border);
             color: var(--text);
             border-radius: 8px;
-            padding: 10px 0;
+            padding: 10px 14px;
             cursor: pointer;
             font-size: 0.9rem;
             text-align: center;
+            white-space: nowrap;
             transition: background 0.15s;
         }