implement authentication and authorization

public/js/login.js

@@ -0,0 +1,14 @@
+document.getElementById('login-form').addEventListener('submit', async (e) => {
+    e.preventDefault();
+
+    const username = document.getElementById('username').value;
+    const password = document.getElementById('password').value;
+
+    try {
+        const response = await API.request('POST', '/auth/login', { username, password });
+        localStorage.setItem('sessionToken', response.token);
+        window.location.href = '/';
+    } catch (err) {
+        document.getElementById('login-error').textContent = 'Login failed: ' + err.message;
+    }
+});