feat(ui): emphasize task creation and add empty-list actions (#1505)

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

@@ -0,0 +1,42 @@
+import 'package:shadcn_flutter/shadcn_flutter.dart' as shad;
+import 'package:flutter/material.dart' show Icons;
+import 'package:flutter/widgets.dart';
+
+import '../../../../l10n/l10n.dart';
+import '../../../../shared/theme/app_design_tokens.dart';
+import '../../../../shared/widgets/app_primary_button.dart';
+
+/// Shared creation action for task headers and empty-list guidance.
+class TaskCreateButton extends StatelessWidget {
+  const TaskCreateButton({super.key, required this.onPressed, this.minHeight = 0, this.compact = false});
+
+  final VoidCallback onPressed;
+  final double minHeight;
+  final bool compact;
+
+  @override
+  Widget build(BuildContext context) {
+    return ConstrainedBox(
+      constraints: BoxConstraints(minHeight: minHeight),
+      child: AppPrimaryButton(
+        onPressed: onPressed,
+        size: compact ? shad.ButtonSize.small : shad.ButtonSize.normal,
+        child: Row(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(Icons.add, size: compact ? 16 : null),
+            SizedBox(width: compact ? AppDesignTokens.space4 : AppDesignTokens.space8),
+            Flexible(
+              child: Text(
+                context.l10n.create,
+                maxLines: 1,
+                overflow: TextOverflow.ellipsis,
+                style: compact ? const TextStyle(fontSize: 13) : null,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

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

@@ -0,0 +1,49 @@
+import 'package:shadcn_flutter/shadcn_flutter.dart';
+
+import '../../../../l10n/l10n.dart';
+import '../../../../shared/theme/app_palette.dart';
+import '../../../../shared/widgets/app_tooltip.dart';
+
+/// Keeps the action inside the localized sentence, including RTL word order.
+class TaskEmptyCreateHint extends StatelessWidget {
+  const TaskEmptyCreateHint({super.key, required this.onCreateTask});
+
+  final VoidCallback onCreateTask;
+
+  @override
+  Widget build(BuildContext context) {
+    const actionMarker = '\uFFFC';
+    final parts = context.l10n.emptyTaskCreateHint(actionMarker).split(actionMarker);
+    return Text.rich(
+      TextSpan(
+        children: [
+          TextSpan(text: parts.first.trimRight()),
+          WidgetSpan(
+            alignment: PlaceholderAlignment.middle,
+            child: Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 8),
+              child: AppTooltip(
+                message: context.l10n.create,
+                child: Semantics(
+                  label: context.l10n.create,
+                  child: SizedBox.square(
+                    dimension: 30,
+                    child: IconButton.outline(
+                      key: const ValueKey('tasks-empty-create-button'),
+                      density: ButtonDensity.compact,
+                      onPressed: onCreateTask,
+                      icon: const Icon(Icons.add, size: 16),
+                    ),
+                  ),
+                ),
+              ),
+            ),
+          ),
+          TextSpan(text: parts.last.trimLeft()),
+        ],
+      ),
+      textAlign: TextAlign.center,
+      style: TextStyle(color: AppPalette.of(context).textMuted, fontSize: 13),
+    );
+  }
+}

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

@@ -1,35 +1,45 @@
 import 'package:flutter/widgets.dart';
 
 import '../../../../shared/theme/app_palette.dart';
+import '../../../../shared/theme/app_design_tokens.dart';
+import 'task_empty_create_hint.dart';
 import '../../../../l10n/l10n.dart';
 
 class TaskEmptyState extends StatelessWidget {
-  const TaskEmptyState({super.key, this.message});
+  const TaskEmptyState({super.key, this.message, this.onCreateTask});
 
   final String? message;
+  final VoidCallback? onCreateTask;
 
   @override
   Widget build(BuildContext context) {
     final palette = AppPalette.of(context);
     return Center(
-      child: ConstrainedBox(
-        constraints: const BoxConstraints(maxWidth: 360),
-        child: Padding(
-          padding: const EdgeInsets.all(24),
-          child: Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              CustomPaint(
-                key: const ValueKey('task-empty-illustration'),
-                size: const Size(148, 108),
-                painter: _TaskEmptyIllustrationPainter(palette: palette),
-              ),
-              const SizedBox(height: 18),
-              Text(
-                message ?? context.l10n.emptyTaskList,
-                style: TextStyle(color: palette.textPrimary, fontSize: 17, fontWeight: FontWeight.w700),
-              ),
-            ],
+      child: SingleChildScrollView(
+        child: ConstrainedBox(
+          constraints: const BoxConstraints(maxWidth: 360),
+          child: Padding(
+            padding: const EdgeInsets.all(24),
+            child: Column(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                CustomPaint(
+                  key: const ValueKey('task-empty-illustration'),
+                  size: const Size(148, 108),
+                  painter: _TaskEmptyIllustrationPainter(palette: palette),
+                ),
+                const SizedBox(height: 18),
+                Text(
+                  message ?? context.l10n.emptyTaskList,
+                  textAlign: TextAlign.center,
+                  style: TextStyle(color: palette.textPrimary, fontSize: 17, fontWeight: FontWeight.w700),
+                ),
+                if (onCreateTask != null) ...[
+                  const SizedBox(height: AppDesignTokens.space24),
+                  TaskEmptyCreateHint(onCreateTask: onCreateTask!),
+                ],
+              ],
+            ),
           ),
         ),
       ),