fix: soporte siempre visible + perfil mejorado

- Setting: lee support_title/description/days/hours/email/phone
- SettingsProvider: fallback a Setting vacio si no hay datos en DB
- SupportView: guard para settings null
- Avatar: ui-avatars.com como imagen por defecto (con nombre)
- Perfil: seccion correo como ExpansionTile (acordeon)
  paso 1: email+contrasena+confirmar → Enviar codigo
  paso 2: ingresar codigo de 6 digitos → Verificar (verde)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ui/shared/widgets/navbar_avatar.dart

@@ -11,6 +11,10 @@ class NavbarAvatar extends StatelessWidget {
   Widget build(BuildContext context) {
     final user = Provider.of<AuthProvider>(context).user!;
     final hasPicture = user.picture != null && user.picture!.isNotEmpty;
+    final encoded = Uri.encodeComponent(user.name.isEmpty ? 'U' : user.name);
+    final fallbackUrl =
+        'https://ui-avatars.com/api/?name=$encoded&background=42A4EF&color=fff&size=80&bold=true&rounded=true';
+    final imageUrl = hasPicture ? user.picture! : fallbackUrl;
 
     return MouseRegion(
       cursor: SystemMouseCursors.click,
@@ -20,13 +24,12 @@ class NavbarAvatar extends StatelessWidget {
           width: 36,
           height: 36,
           child: ClipOval(
-            child: hasPicture
-                ? Image.network(
-                    user.picture!,
-                    fit: BoxFit.cover,
-                    errorBuilder: (_, __, ___) => _InitialsAvatar(name: user.name),
-                  )
-                : _InitialsAvatar(name: user.name),
+            child: Image.network(
+              imageUrl,
+              fit: BoxFit.cover,
+              errorBuilder: (_, __, ___) =>
+                  Image.network(fallbackUrl, fit: BoxFit.cover),
+            ),
           ),
         ),
       ),
@@ -34,46 +37,3 @@ class NavbarAvatar extends StatelessWidget {
   }
 }
 
-class _InitialsAvatar extends StatelessWidget {
-  final String name;
-  const _InitialsAvatar({required this.name});
-
-  String get _initials {
-    final parts = name.trim().split(RegExp(r'\s+'));
-    if (parts.isEmpty || parts.first.isEmpty) return '?';
-    if (parts.length == 1) return parts.first[0].toUpperCase();
-    return (parts.first[0] + parts.last[0]).toUpperCase();
-  }
-
-  Color get _bgColor {
-    final colors = [
-      const Color(0xFF6366F1), // indigo
-      const Color(0xFF8B5CF6), // violet
-      const Color(0xFFEC4899), // pink
-      const Color(0xFF14B8A6), // teal
-      const Color(0xFFF59E0B), // amber
-      const Color(0xFF10B981), // emerald
-      const Color(0xFFEF4444), // red
-      const Color(0xFF3B82F6), // blue
-    ];
-    final index = name.isEmpty ? 0 : name.codeUnitAt(0) % colors.length;
-    return colors[index];
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return Container(
-      color: _bgColor,
-      child: Center(
-        child: Text(
-          _initials,
-          style: const TextStyle(
-            color: Colors.white,
-            fontSize: 13,
-            fontWeight: FontWeight.bold,
-          ),
-        ),
-      ),
-    );
-  }
-}