fix(ui): improve cross-platform text input behavior (#1477)

ui/flutter/lib/features/tasks/presentation/pages/create_task_window_page.dart

@@ -32,6 +32,7 @@ import '../../../../shared/widgets/app_http_headers_editor.dart';
 import '../../../../shared/widgets/app_number_input.dart';
 import '../../../../shared/widgets/app_path_picker_field.dart';
 import '../../../../shared/widgets/app_primary_button.dart';
+import '../../../../shared/widgets/app_text_field.dart';
 import '../../../../shared/widgets/app_tooltip.dart';
 import '../../../../shared/widgets/app_toast.dart';
 import '../../../../l10n/l10n.dart';
@@ -257,7 +258,12 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
     final page = Scaffold(
       backgroundColor: palette.sideBg,
       child: Padding(
-        padding: EdgeInsets.only(top: AppWindowChrome.reservesHeaderInset ? AppDesignTokens.windowHeaderHeight : 0),
+        key: const ValueKey('create-task-safe-content'),
+        padding: EdgeInsets.only(
+          top: AppWindowChrome.reservesHeaderInset
+              ? AppDesignTokens.windowHeaderHeight
+              : MediaQuery.paddingOf(context).top,
+        ),
         child: Column(
           children: [
             Container(
@@ -300,7 +306,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
                             children: [
                               SizedBox(
                                 height: 120,
-                                child: TextField(
+                                child: AppTextField(
                                   controller: _urlController,
                                   hintText: context.l10n.pasteDownloadLinks,
                                   keyboardType: TextInputType.multiline,
@@ -645,7 +651,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
                                 label: context.l10n.trackers,
                                 child: SizedBox(
                                   height: 96,
-                                  child: TextField(
+                                  child: AppTextField(
                                     controller: _trackersController,
                                     hintText: context.l10n.oneTrackerPerLine,
                                     keyboardType: TextInputType.multiline,
@@ -1233,7 +1239,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
                   children: [
                     SizedBox(
                       height: 38,
-                      child: TextField(
+                      child: AppTextField(
                         key: const ValueKey('create-history-filter'),
                         controller: filterController,
                         placeholder: Text(
@@ -1660,7 +1666,7 @@ class _WindowTextField extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final palette = AppPalette.of(context);
-    return TextField(
+    return AppTextField(
       controller: controller,
       hintText: hintText,
       keyboardType: keyboardType,

ui/flutter/lib/features/tasks/presentation/widgets/task_drawer.dart

@@ -9,6 +9,7 @@ import 'package:shadcn_flutter/shadcn_flutter.dart' as shad;
 import '../../../../shared/theme/app_design_tokens.dart';
 import '../../../../shared/theme/app_palette.dart';
 import '../../../../shared/widgets/app_copy_icon_button.dart';
+import '../../../../shared/widgets/app_text_field.dart';
 import '../../../../shared/widgets/app_tooltip.dart';
 import '../../../../shared/widgets/detail/app_detail_surface.dart';
 import '../../../../core/utils/text_wrap.dart';
@@ -512,7 +513,7 @@ class _EditableUrlBlock extends StatelessWidget {
               children: [
                 SizedBox(
                   height: 76,
-                  child: shad.TextField(
+                  child: AppTextField(
                     controller: controller,
                     minLines: null,
                     maxLines: null,

ui/flutter/lib/features/tasks/presentation/widgets/task_update_url_dialog.dart

@@ -4,6 +4,7 @@ import 'package:shadcn_flutter/shadcn_flutter.dart' hide Column, Expanded, Row;
 import '../../../../shared/theme/app_palette.dart';
 import '../../../../shared/widgets/app_http_headers_editor.dart';
 import '../../../../shared/widgets/app_primary_button.dart';
+import '../../../../shared/widgets/app_text_field.dart';
 import '../../../../l10n/l10n.dart';
 import '../../domain/task_record.dart';
 
@@ -47,7 +48,7 @@ Future<TaskUrlUpdate?> showTaskUpdateUrlDialog(BuildContext context, TaskRecord
                   children: [
                     Text(dialogContext.l10n.downloadLink, style: TextStyle(color: palette.textPrimary, fontSize: 12)),
                     const SizedBox(height: 6),
-                    TextField(controller: urlController),
+                    AppTextField(controller: urlController),
                     const SizedBox(height: 18),
                     AppHttpHeadersEditor(
                       controller: headersController,