fix: withOpacity au lieu de withValues (API Flutter 3.24)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/screens/login_screen.dart

@@ -42,7 +42,7 @@ class _LoginScreenState extends State<LoginScreen> {
           gradient: LinearGradient(
             begin: Alignment.topLeft,
             end: Alignment.bottomRight,
-            colors: [scheme.primary.withValues(alpha: 0.25), scheme.surface],
+            colors: [scheme.primary.withOpacity(0.25), scheme.surface],
           ),
         ),
         child: SafeArea(

lib/widgets/server_card.dart

@@ -51,7 +51,7 @@ class ServerCard extends StatelessWidget {
                       if (server.subtitle != null)
                         Text(server.subtitle!,
                             style: TextStyle(
-                                color: Colors.white.withValues(alpha: 0.75), fontSize: 13)),
+                                color: Colors.white.withOpacity(0.75), fontSize: 13)),
                     ],
                   ),
                 ),
@@ -72,7 +72,7 @@ class ServerCard extends StatelessWidget {
                   Expanded(
                     child: Text(server.connect!,
                         style: TextStyle(
-                            color: Colors.white.withValues(alpha: 0.7),
+                            color: Colors.white.withOpacity(0.7),
                             fontFamily: 'monospace',
                             fontSize: 12),
                         maxLines: 1,
@@ -113,7 +113,7 @@ class _Icon extends StatelessWidget {
   }
 
   Widget _fallbackBox() => Container(
-        color: Colors.white.withValues(alpha: 0.15),
+        color: Colors.white.withOpacity(0.15),
         child: Icon(fallback, color: Colors.white, size: 28),
       );
 }
@@ -129,7 +129,7 @@ class _StatusPill extends StatelessWidget {
     return Container(
       padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
       decoration: BoxDecoration(
-        color: color.withValues(alpha: 0.22),
+        color: color.withOpacity(0.22),
         borderRadius: BorderRadius.circular(999),
         border: Border.all(color: color, width: 1),
       ),
@@ -156,7 +156,7 @@ class _ToggleButton extends StatelessWidget {
     return FilledButton.icon(
       onPressed: busy ? null : onToggle,
       style: FilledButton.styleFrom(
-        backgroundColor: up ? Colors.white.withValues(alpha: 0.9) : Colors.white,
+        backgroundColor: up ? Colors.white.withOpacity(0.9) : Colors.white,
         foregroundColor: up ? const Color(0xFFB3261E) : const Color(0xFF1B5E20),
       ),
       icon: busy