feat(playground): add syntax highlighting and improve console output

- Add CodeMirror editor with FratmScript syntax highlighting
- Custom color theme matching COSS UI (pink keywords, green strings, etc.)
- Line numbers, active line highlight, Ctrl+Enter to run
- Improved console output with Chrome DevTools-like styling
- Icons for log/warn/error entries
- Color-coded values (strings green, numbers amber, etc.)
- Better error display with suggestions

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kkratterf

packages/playground/package.json

@@ -10,6 +10,11 @@
   },
   "dependencies": {
     "@base-ui/react": "^1.0.0-alpha.10",
+    "@codemirror/commands": "^6.10.1",
+    "@codemirror/language": "^6.12.1",
+    "@codemirror/state": "^6.5.4",
+    "@codemirror/view": "^6.39.11",
+    "@lezer/highlight": "^1.2.3",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "lucide-react": "^0.468.0",