feat: add 'Keep me logged in' checkbox to login form

- index.html: checkbox between password field and login button
- app.js: reads #remember-me and passes rememberMe in POST body
- auth.js: rememberMe=true sets 30-day maxAge; false = session cookie
  (expires when browser closes)
- style.css: .form-group--checkbox and .checkbox-label styles

public/app.js

@@ -136,6 +136,7 @@ async function handleLogin(e) {
   
   const username = document.getElementById('username').value;
   const password = document.getElementById('password').value;
+  const rememberMe = document.getElementById('remember-me').checked;
   
   try {
     const response = await fetch('/api/auth/login', {
@@ -143,7 +144,7 @@ async function handleLogin(e) {
       headers: {
         'Content-Type': 'application/json'
       },
-      body: JSON.stringify({ username, password })
+      body: JSON.stringify({ username, password, rememberMe })
     });
     
     const data = await response.json();

public/index.html

@@ -31,6 +31,12 @@
                         <label for="password">Password:</label>
                         <input type="password" id="password" name="password" required>
                     </div>
+                    <div class="form-group form-group--checkbox">
+                        <label class="checkbox-label">
+                            <input type="checkbox" id="remember-me" name="rememberMe">
+                            <span>Keep me logged in</span>
+                        </label>
+                    </div>
                     <button type="submit" class="login-btn">Login</button>
                 </form>
                 <div id="login-error" class="error-message" style="display: none;"></div>

public/style.css

@@ -612,6 +612,32 @@ body {
   border-color: var(--accent);
 }
 
+.form-group--checkbox {
+  margin-bottom: 20px;
+}
+
+.checkbox-label {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  cursor: pointer;
+  font-size: 0.9rem;
+  color: var(--text-secondary);
+  user-select: none;
+}
+
+.checkbox-label input[type="checkbox"] {
+  width: 16px;
+  height: 16px;
+  accent-color: var(--accent);
+  cursor: pointer;
+  flex-shrink: 0;
+}
+
+.checkbox-label span {
+  line-height: 1;
+}
+
 .login-btn {
   width: 100%;
   padding: 10px;

server/routes/auth.js

@@ -34,7 +34,7 @@ const loginLimiter = rateLimit({
 // Authenticate user with Emby
 router.post('/login', loginLimiter, async (req, res) => {
   try {
-    const { username, password } = req.body;
+    const { username, password, rememberMe } = req.body;
     
     console.log(`[Auth] Attempting login for user: ${username}`);
     
@@ -68,15 +68,20 @@ router.post('/login', loginLimiter, async (req, res) => {
     storeToken(user.Id, authData.AccessToken);
     
     // Set authentication cookie (signed when COOKIE_SECRET is set).
+    // rememberMe=true  → persistent cookie, expires in 30 days
+    // rememberMe=false → session cookie, expires when browser closes
     const cookiePayload = JSON.stringify({ id: user.Id, name: user.Name, isAdmin });
     const signed = !!process.env.COOKIE_SECRET;
-    res.cookie('emby_user', cookiePayload, {
+    const cookieOptions = {
       httpOnly: true,
       secure: process.env.NODE_ENV === 'production',
       sameSite: 'strict',
-      signed,
-      maxAge: 24 * 60 * 60 * 1000 // 24 hours
-    });
+      signed
+    };
+    if (rememberMe) {
+      cookieOptions.maxAge = 30 * 24 * 60 * 60 * 1000; // 30 days
+    }
+    res.cookie('emby_user', cookiePayload, cookieOptions);
     
     res.json({
       success: true,