Hide native title text on macOS overlay title bar.

The native "MouseTerm" title text was rendering on top of our custom
AppBar content. Setting hiddenTitle: true hides the native text while
keeping the title visible in the dock and app switcher.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nedtwigg

standalone/src-tauri/tauri.conf.json

@@ -14,6 +14,7 @@
       {
         "title": "MouseTerm",
         "titleBarStyle": "Overlay",
+        "hiddenTitle": true,
         "width": 1200,
         "height": 800,
         "minWidth": 800,