style(theme): 客户端切换深色视觉风格

lib/pages/account/account_deactivate_page.dart

@@ -51,7 +51,7 @@ class _AccountDeactivatePageState extends State<AccountDeactivatePage> {
     final signedIn = context.watch<AuthController>().isSignedIn;
     final canShow = signedIn || _logic.scheduledAt != null;
     return Theme(
-      data: AppTheme.light(),
+      data: AppTheme.dark(),
       child: PlainPageScaffold(
         pageKey: const Key('account-deactivate-page'),
         backKey: const Key('account-deactivate-back'),

lib/pages/account/account_devices_page.dart

@@ -51,7 +51,7 @@ class _AccountDevicesPageState extends State<AccountDevicesPage> {
     final l10n = AppLocalizations.of(context)!;
     final signedIn = context.watch<AuthController>().isSignedIn;
     return Theme(
-      data: AppTheme.light(),
+      data: AppTheme.dark(),
       child: PlainPageScaffold(
         pageKey: const Key('account-devices-page'),
         backKey: const Key('account-devices-back'),

lib/pages/account/account_export_page.dart

@@ -52,7 +52,7 @@ class _AccountExportPageState extends State<AccountExportPage> {
     final l10n = AppLocalizations.of(context)!;
     final signedIn = context.watch<AuthController>().isSignedIn;
     return Theme(
-      data: AppTheme.light(),
+      data: AppTheme.dark(),
       child: PlainPageScaffold(
         pageKey: const Key('account-export-page'),
         backKey: const Key('account-export-back'),

lib/pages/account/account_profile_page.dart

@@ -70,7 +70,7 @@ class _AccountProfilePageState extends State<AccountProfilePage> {
     final l10n = AppLocalizations.of(context)!;
     final signedIn = context.watch<AuthController>().isSignedIn;
     return Theme(
-      data: AppTheme.light(),
+      data: AppTheme.dark(),
       child: PlainPageScaffold(
         pageKey: const Key('account-profile-page'),
         backKey: const Key('account-profile-back'),
@@ -181,6 +181,7 @@ class _AccountProfilePageState extends State<AccountProfilePage> {
 
   Widget _genderField(AppLocalizations l10n) => DropdownButtonFormField<String>(
     key: const Key('account-gender'),
+    isExpanded: true,
     initialValue: _gender,
     decoration: InputDecoration(labelText: l10n.accountGender),
     items: [