feat: signin page keyboard on IOS

frontend/lib/main.dart

@@ -407,6 +407,7 @@ class _SignInPageState extends State<SignInPage> {
     return PopScope(
       canPop: false, // Prevent back navigation from sign in page
       child: Scaffold(
+        resizeToAvoidBottomInset: false,
         body: Container(
           decoration: BoxDecoration(
             gradient: LinearGradient(
@@ -442,6 +443,7 @@ class _SignInPageState extends State<SignInPage> {
 
                 // Content
                 Expanded(
+                  child: SingleChildScrollView(
                     child: Container(
                       margin: EdgeInsets.all(16),
                       padding: EdgeInsets.all(24),
@@ -643,12 +645,13 @@ class _SignInPageState extends State<SignInPage> {
                             ],
                           ),
 
-                          Spacer(),
+                          SizedBox(height: 40),
                         ],
                       ),
                       ),
                     ),
                   ),
+                ),
               ],
             ),
           ),