feat: add depth to game

lib/features/lobby/lobby_screen.dart

@@ -195,13 +195,59 @@ class _MenuButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    // رنگِ تیره‌ترِ پایه برای بِوِل (لبه‌ی پایینیِ برجسته).
+    final dark = Color.lerp(color, Colors.black, 0.45)!;
+    final light = Color.lerp(color, Colors.white, 0.12)!;
     return SizedBox(
       width: 280,
-      child: ElevatedButton.icon(
-        style: ElevatedButton.styleFrom(backgroundColor: color),
-        onPressed: onTap,
-        icon: Icon(icon, color: AppColors.gold),
-        label: Text(label),
+      child: Material(
+        color: Colors.transparent,
+        borderRadius: BorderRadius.circular(16),
+        child: InkWell(
+          borderRadius: BorderRadius.circular(16),
+          onTap: onTap,
+          child: Container(
+            padding: const EdgeInsets.symmetric(vertical: 15),
+            decoration: BoxDecoration(
+              gradient: LinearGradient(
+                begin: Alignment.topCenter,
+                end: Alignment.bottomCenter,
+                colors: [light, color, dark],
+                stops: const [0, 0.5, 1],
+              ),
+              borderRadius: BorderRadius.circular(16),
+              border: Border.all(color: AppColors.gold, width: 1.6),
+              boxShadow: [
+                BoxShadow(
+                  color: Colors.black.withValues(alpha: 0.55),
+                  blurRadius: 10,
+                  offset: const Offset(0, 5),
+                ),
+                // هایلایتِ بالا برای حسِ شیشه‌ای/برجسته.
+                BoxShadow(
+                  color: Colors.white.withValues(alpha: 0.12),
+                  blurRadius: 1,
+                  offset: const Offset(0, 1),
+                  spreadRadius: -1,
+                ),
+              ],
+            ),
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Icon(icon, color: AppColors.gold),
+                const SizedBox(width: 10),
+                Text(label,
+                    style: const TextStyle(
+                      color: AppColors.text,
+                      fontSize: 18,
+                      fontWeight: FontWeight.bold,
+                      shadows: [Shadow(color: Colors.black54, blurRadius: 3)],
+                    )),
+              ],
+            ),
+          ),
+        ),
       ),
     );
   }