fix drawer icon color

the drawer icon will now follow the nearest IconThemeData. Only the gamePage nad helPage do override them.

cleanup code

src/ui/flutter_app/lib/screens/game_page/game_page.dart

@@ -22,7 +22,6 @@ import 'package:fluentui_system_icons/fluentui_system_icons.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:sanmill/generated/intl/l10n.dart';
-import 'package:sanmill/main.dart';
 import 'package:sanmill/mill/game.dart';
 import 'package:sanmill/mill/position.dart';
 import 'package:sanmill/mill/rule.dart';
@@ -1346,39 +1345,30 @@ class _GamePageState extends State<GamePage>
   }
 
   IconData get iconArrow {
-    IconData iconArrow = FluentIcons.code_24_regular;
-
     if (gameInstance.position.phase == Phase.gameOver) {
       switch (gameInstance.position.winner) {
         case PieceColor.white:
-          iconArrow = ltr
+          return ltr
               ? FluentIcons.toggle_left_24_regular
               : FluentIcons.toggle_right_24_regular;
-          break;
         case PieceColor.black:
-          iconArrow = ltr
+          return ltr
               ? FluentIcons.toggle_right_24_regular
               : FluentIcons.toggle_left_24_regular;
-          break;
         default:
-          iconArrow = FluentIcons.handshake_24_regular;
+          return FluentIcons.handshake_24_regular;
-          break;
       }
     } else {
       switch (gameInstance.sideToMove) {
         case PieceColor.white:
-          iconArrow = FluentIcons.chevron_left_24_regular;
+          return FluentIcons.chevron_left_24_regular;
-          break;
-        case PieceColor.black:
-          iconArrow = FluentIcons.chevron_right_24_regular;
-          break;
-        default:
-          iconArrow = FluentIcons.code_24_regular;
-          break;
-      }
-    }
 
-    return iconArrow;
+        case PieceColor.black:
+          return FluentIcons.chevron_right_24_regular;
+        default:
+          return FluentIcons.code_24_regular;
+      }
+    }
   }
 
   Widget get board {
@@ -1645,10 +1635,6 @@ class _GamePageState extends State<GamePage>
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
-    routeObserver.subscribe(
-      this,
-      ModalRoute.of(context)! as PageRoute<dynamic>,
-    );
     screenPaddingH = _screenPaddingH;
     ltr = Directionality.of(context) == TextDirection.ltr;
   }
@@ -1664,6 +1650,9 @@ class _GamePageState extends State<GamePage>
         leading: DrawerIcon.of(context)?.icon,
         backgroundColor: Colors.transparent,
         elevation: 0.0,
+        iconTheme: IconThemeData(
+          color: AppTheme.drawerAnimationIconColor,
+        ),
       ),
       extendBodyBehindAppBar: true,
       backgroundColor: LocalDatabaseService.colorSettings.darkBackgroundColor,
@@ -1688,7 +1677,6 @@ class _GamePageState extends State<GamePage>
     disposed = true;
     _engine.shutdown();
     _animationController.dispose();
-    routeObserver.unsubscribe(this);
     LocalDatabaseService.listenPreferences.removeListener(_refeshEngine);
     super.dispose();
   }

src/ui/flutter_app/lib/screens/help_screen.dart

@@ -20,6 +20,9 @@ class HelpScreen extends StatelessWidget {
             color: AppTheme.helpTextColor,
           ),
         ),
+        iconTheme: IconThemeData(
+          color: AppTheme.helpTextColor,
+        ),
       ),
       backgroundColor: LocalDatabaseService.colorSettings.darkBackgroundColor,
       body: SingleChildScrollView(

src/ui/flutter_app/lib/shared/custom_drawer/src/widget.dart

@@ -126,7 +126,6 @@ class _CustomDrawerState extends State<CustomDrawer>
     final _drawerOverlay = IconButton(
       icon: AnimatedIcon(
         icon: AnimatedIcons.arrow_menu,
-        color: AppTheme.drawerAnimationIconColor,
         progress: ReverseAnimation(_animationController),
       ),
       tooltip: MaterialLocalizations.of(context).openAppDrawerTooltip,