feat: Add JWT authentication to backend, configure frontend API client, fix streak layout

src/lib/apiClient.ts

@@ -0,0 +1,27 @@
+export async function fetchWithAuth(url: string, options: RequestInit = {}): Promise<Response> {
+  const isServer = typeof window === 'undefined';
+  
+  if (isServer) {
+    // If we're on the server-side, we should pass along headers from next/headers
+    // or just let it fall back to standard fetch if no auth is needed for server-side fetches.
+    // For this app, most data fetching seems to be client-side.
+    return fetch(url, options);
+  }
+
+  // Get token from localStorage
+  const token = localStorage.getItem('active_session_token');
+
+  // Prepare headers
+  const headers = new Headers(options.headers || {});
+  
+  // Apply token if it exists
+  if (token) {
+    headers.set('Authorization', `Bearer ${token}`);
+  }
+
+  // Perform fetch with updated headers
+  return fetch(url, {
+    ...options,
+    headers,
+  });
+}