Enhance user authentication handling by adding authMethod to UserModel and updating ProfileContent to display authentication method details.

lib/components/signup/sign_up_platform_content.dart

@@ -85,10 +85,10 @@ class _SignUpPlatformContentState extends State<SignUpPlatformContent> {
     Color platformColor = widget.platform == 'google'
         ? Colors.red
         : Colors.black;
-    IconData platformIcon = widget.platform == 'google'
-        ? Icons.g_mobiledata
-        : Icons.apple;
     String platformName = widget.platform == 'google' ? 'Google' : 'Apple';
+    String platformIcon = widget.platform == 'google'
+        ? 'assets/icons/google.png'
+        : 'assets/icons/apple_white.png';
 
     return Container(
       padding: const EdgeInsets.all(16),
@@ -103,7 +103,11 @@ class _SignUpPlatformContentState extends State<SignUpPlatformContent> {
       ),
       child: Row(
         children: [
-          Icon(platformIcon, color: platformColor, size: 24),
+          Image.asset(
+            platformIcon,
+            height: 24,
+            width: 24,
+          ),
           const SizedBox(width: 8),
           Text(
             'Connecté avec $platformName',