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

ui/error-page.ts

@@ -5,7 +5,7 @@ export const component: ClosureComponent = (): Component => {
   return {
     view: function (vnode) {
       document.title = "Error! - GenieACS";
-      return m("p.error", vnode.attrs["error"]);
+      return m("p.text-sm font-bold text-red-500", vnode.attrs["error"]);
     },
   };
 };