New UI (#157, #164)

- Add a react UI to replace the plain HTML one. 
- Serve as a foundation for better GUI interactions

ui/src/App.tsx

@@ -0,0 +1,44 @@
+import { BrowserRouter as Router, Routes, Route, Navigate, NavLink } from "react-router-dom";
+import { useTheme } from "./contexts/ThemeProvider";
+import { APIProvider } from "./contexts/APIProvider";
+import LogViewerPage from "./pages/LogViewer";
+import ModelPage from "./pages/Models";
+
+function App() {
+  const theme = useTheme();
+  return (
+    <Router basename="/ui/">
+      <APIProvider>
+        <div>
+          <nav className="bg-surface border-b border-border p-4">
+            <div className="flex items-center justify-between mx-auto px-4">
+              <h1>llama-swap</h1>
+              <div className="flex space-x-4">
+                <NavLink to="/" className={({ isActive }) => (isActive ? "navlink active" : "navlink")}>
+                  Logs
+                </NavLink>
+
+                <NavLink to="/models" className={({ isActive }) => (isActive ? "navlink active" : "navlink")}>
+                  Models
+                </NavLink>
+                <button className="btn btn--sm" onClick={theme.toggleTheme}>
+                  {theme.isDarkMode ? "🌙" : "☀️"}
+                </button>
+              </div>
+            </div>
+          </nav>
+
+          <main className="mx-auto py-4 px-4">
+            <Routes>
+              <Route path="/" element={<LogViewerPage />} />
+              <Route path="/models" element={<ModelPage />} />
+              <Route path="*" element={<Navigate to="/" replace />} />
+            </Routes>
+          </main>
+        </div>
+      </APIProvider>
+    </Router>
+  );
+}
+
+export default App;