feat(ui): redesign UI with Tailwind CSS, CodeMirror 6, and new layout

- Replace all hand-written CSS with Tailwind utility classes
- Upgrade CodeMirror 5 to CodeMirror 6 (scoped @codemirror/* packages)
- Redesign layout with responsive sidebar navigation using JSX/Mithril
- Flatten admin routes (e.g. /admin/presets -> /presets)
- Add "remember me" login option with 2-week persistent cookie
- Add delete confirmation dialogs across admin pages
- Upgrade esbuild from 0.21 to 0.27 and update browser targets
- Add Inter and Roboto Mono variable fonts with subset script

tsconfig.json

@@ -12,7 +12,9 @@
     "isolatedModules": true,
     "noEmit": true,
     "allowImportingTsExtensions": true,
-    "skipLibCheck": true
+    "skipLibCheck": true,
+    "jsx": "react",
+    "jsxFactory": "m"
   },
   "include": [
     "./bin/*.ts",