Update login screen copy and logo style

- Logo: extra bold 'i' (w800) in tighter rounded square
- Changed 'Sign in to your inou account' → 'Enter your email to continue'
- Changed 'Welcome' → 'Welcome to inou'
- Changed 'Sign in with Biometrics' → 'Use Biometrics'

lib/features/auth/login_screen.dart

@@ -212,7 +212,7 @@ class _LoginScreenState extends State<LoginScreen> {
                 
                 // Title
                 Text(
-                  _codeSent ? 'Check your email' : 'Welcome',
+                  _codeSent ? 'Check your email' : 'Welcome to inou',
                   style: Theme.of(context).textTheme.headlineLarge,
                   textAlign: TextAlign.center,
                 ),
@@ -220,7 +220,7 @@ class _LoginScreenState extends State<LoginScreen> {
                 Text(
                   _codeSent 
                       ? 'Enter the 6-digit code sent to\n$_sentToEmail'
-                      : 'Sign in to your inou account',
+                      : 'Enter your email to continue',
                   style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                     color: InouColors.textMuted,
                   ),
@@ -352,15 +352,15 @@ class _LoginScreenState extends State<LoginScreen> {
       margin: const EdgeInsets.symmetric(horizontal: 120),
       decoration: BoxDecoration(
         color: InouColors.accent,
-        borderRadius: BorderRadius.circular(20),
+        borderRadius: BorderRadius.circular(16),
       ),
       child: const Center(
         child: Text(
           'i',
           style: TextStyle(
             color: Colors.white,
-            fontSize: 48,
-            fontWeight: FontWeight.w300,
+            fontSize: 52,
+            fontWeight: FontWeight.w800,
           ),
         ),
       ),
@@ -430,7 +430,7 @@ class _LoginScreenState extends State<LoginScreen> {
         future: _biometricService.getBiometricTypeName(),
         builder: (context, snapshot) {
           final name = snapshot.data ?? 'Biometrics';
-          return Text('Sign in with $name');
+          return Text('Use $name');
         },
       ),
       style: OutlinedButton.styleFrom(