refactor(ui): unify theme styling and enlarge profile button

Centralize existing Material and Mornye layout metrics in AppTokens and share adaptive icon selection. Enlarge the Home profile avatar to 44 dp with a 56 dp touch target.

lib/screens/settings/about_page.dart

@@ -697,7 +697,7 @@ class _AboutSettingsItem extends StatelessWidget {
                   width: 40,
                   height: 40,
                   child: Icon(
-                    context.isMornye ? mornyeIconFor(icon) : icon,
+                    context.adaptiveIcon(icon),
                     color: context.isMornye
                         ? colorScheme.primary
                         : colorScheme.onSurfaceVariant,

lib/screens/settings/app_settings_page.dart

@@ -282,9 +282,7 @@ class _UpdateChannelSelector extends StatelessWidget {
           Row(
             children: [
               Icon(
-                context.isMornye
-                    ? mornyeIconFor(Icons.new_releases)
-                    : Icons.new_releases,
+                context.adaptiveIcon(Icons.new_releases),
                 color: context.isMornye
                     ? colorScheme.primary
                     : colorScheme.onSurfaceVariant,
@@ -389,9 +387,7 @@ class _VerificationBrowserModeSelector extends StatelessWidget {
               Row(
                 children: [
                   Icon(
-                    context.isMornye
-                        ? mornyeIconFor(Icons.open_in_browser)
-                        : Icons.open_in_browser,
+                    context.adaptiveIcon(Icons.open_in_browser),
                     color: context.isMornye
                         ? colorScheme.primary
                         : colorScheme.onSurfaceVariant,

lib/screens/settings/appearance_settings_page.dart

@@ -709,7 +709,7 @@ class _LanguageSelector extends StatelessWidget {
     final colorScheme = Theme.of(context).colorScheme;
     final content = ListTile(
       leading: Icon(
-        context.isMornye ? mornyeIconFor(Icons.language) : Icons.language,
+        context.adaptiveIcon(Icons.language),
         color: context.isMornye
             ? colorScheme.primary
             : colorScheme.onSurfaceVariant,

lib/screens/settings/extension_detail_page.dart

@@ -594,7 +594,6 @@ class _ExtensionDivider extends StatelessWidget {
   @override
   Widget build(BuildContext context) => Divider(
     height: 1,
-    thickness: context.isMornye ? 0.5 : 1,
     indent: indent,
     endIndent: 16,
     color: context.isMornye
@@ -706,7 +705,7 @@ class _CapabilityItem extends StatelessWidget {
           child: Row(
             children: [
               Icon(
-                context.isMornye ? mornyeIconFor(icon) : icon,
+                context.adaptiveIcon(icon),
                 color: context.isMornye || enabled
                     ? colorScheme.primary
                     : colorScheme.outline,
@@ -980,7 +979,7 @@ class _PermissionItem extends StatelessWidget {
           child: Row(
             children: [
               Icon(
-                context.isMornye ? mornyeIconFor(icon) : icon,
+                context.adaptiveIcon(icon),
                 color: context.isMornye
                     ? colorScheme.primary
                     : colorScheme.onSurfaceVariant,