remove debug banner on screenshots.

test/screenshot_automation_test.dart

@@ -324,6 +324,7 @@ void main() {
           setDevice(tester);
           await tester.pumpWidget(
             buildApp(
+              debugShowCheckedModeBanner: false,
               initialLocation: '/accounts/acc-1/mailboxes/INBOX/emails',
               overrides: _inboxOverrides(),
               themeMode: themeMode,
@@ -360,6 +361,7 @@ void main() {
           // so GoRouter can pass them to ComposeScreen via state.extra.
           await tester.pumpWidget(
             buildApp(
+              debugShowCheckedModeBanner: false,
               initialLocation: '/accounts/acc-1/mailboxes/INBOX/emails',
               overrides: _composeOverrides(),
               themeMode: themeMode,
@@ -387,6 +389,7 @@ void main() {
           setDevice(tester);
           await tester.pumpWidget(
             buildApp(
+              debugShowCheckedModeBanner: false,
               initialLocation: '/accounts/acc-1/mailboxes',
               overrides: _mailboxOverrides(),
               themeMode: themeMode,
@@ -403,6 +406,7 @@ void main() {
           setDevice(tester);
           await tester.pumpWidget(
             buildApp(
+              debugShowCheckedModeBanner: false,
               initialLocation: '/accounts/acc-1/mailboxes/INBOX/emails',
               overrides: _searchOverrides(),
               themeMode: themeMode,

test/widget/helpers.dart

@@ -422,6 +422,7 @@ Widget buildApp({
   required List<Override> overrides,
   UserPreferencesRepository? userPreferences,
   ThemeMode themeMode = ThemeMode.light,
+  bool debugShowCheckedModeBanner = true,
 }) {
   final testRouter = GoRouter(
     initialLocation: initialLocation,
@@ -546,6 +547,7 @@ Widget buildApp({
     child: MaterialApp.router(
       routerConfig: testRouter,
       themeMode: themeMode,
+      debugShowCheckedModeBanner: debugShowCheckedModeBanner,
       theme: ThemeData(
         colorScheme: ColorScheme.fromSeed(seedColor: Colors.indigo),
         useMaterial3: true,