feat(web): re-apply dashboard UI improvements on top of i18n

Re-applies changes from #9471 that were overwritten by the i18n PR:

- URL-based routing via react-router-dom (NavLink, Routes, BrowserRouter)
- Replace emoji icons with lucide-react in ConfigPage and SkillsPage
- Sidebar layout for ConfigPage, SkillsPage, and LogsPage
- Custom dropdown Select component (SelectOption) in CronPage
- Remove all non-functional rounded borders across the UI
- Fixed header with proper content offset

Made-with: Cursor

web/src/main.tsx

@@ -1,10 +1,13 @@
 import { createRoot } from "react-dom/client";
+import { BrowserRouter } from "react-router-dom";
 import "./index.css";
 import App from "./App";
 import { I18nProvider } from "./i18n";
 
 createRoot(document.getElementById("root")!).render(
-  <I18nProvider>
-    <App />
-  </I18nProvider>,
+  <BrowserRouter>
+    <I18nProvider>
+      <App />
+    </I18nProvider>
+  </BrowserRouter>,
 );