feat: cleaning code

lib/core/widgets/game_ui.dart

@@ -20,7 +20,7 @@ class GameBackground extends StatelessWidget {
         gradient: RadialGradient(
           center: Alignment(0, -0.4),
           radius: 1.3,
-          colors: [Color(0xFF5A0F1E), Color(0xFF240108)],
+          colors: [Color(0xFF5A0F1E), AppColors.bgDark],
           stops: [0.0, 1.0],
         ),
       ),
@@ -33,7 +33,7 @@ class GameBackground extends StatelessWidget {
                 gradient: RadialGradient(
                   center: Alignment(0, -1.1),
                   radius: 1.0,
-                  colors: [Color(0x33E9B949), Color(0x00000000)],
+                  colors: [AppColors.goldFaint, Color(0x00000000)],
                 ),
               ),
             ),
@@ -65,7 +65,7 @@ class GamePanel extends StatelessWidget {
         gradient: const LinearGradient(
           begin: Alignment.topCenter,
           end: Alignment.bottomCenter,
-          colors: [Color(0xFF6E1322), Color(0xFF3A0A12)],
+          colors: [Color(0xFF6E1322), AppColors.bg],
         ),
         borderRadius: BorderRadius.circular(radius),
         border: Border.all(color: AppColors.gold, width: 2),

lib/core/widgets/rank_badge.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 
+import '../theme/app_theme.dart';
+
 /// نشانِ رتبه (برنز/نقره/طلا/الماس/پادشاه) با رنگ و برچسبِ فارسی.
 class RankBadge extends StatelessWidget {
   final String tier; // bronze..king
@@ -10,7 +12,7 @@ class RankBadge extends StatelessWidget {
   static const _tiers = {
     'bronze': ('برنز', [Color(0xFFCD7F32), Color(0xFF8C5A2B)]),
     'silver': ('نقره', [Color(0xFFBFC6CC), Color(0xFF8A949B)]),
-    'gold': ('طلا', [Color(0xFFFFD54F), Color(0xFFB8860B)]),
+    'gold': ('طلا', [Color(0xFFFFD54F), AppColors.goldDark]),
     'diamond': ('الماس', [Color(0xFF5BE0E6), Color(0xFF1E8A99)]),
     'king': ('پادشاه', [Color(0xFFB388FF), Color(0xFF6A1B9A)]),
   };