feat(flutter): 增加关键操作震动反馈

lib/core/platform/haptics.dart

@@ -0,0 +1,39 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/services.dart';
+
+/// User-action haptic feedback boundary.
+abstract interface class Haptics {
+  /// Feedback for a selection change.
+  Future<void> selectionClick();
+
+  /// Feedback for a primary action.
+  Future<void> lightImpact();
+
+  /// Feedback for a destructive action.
+  Future<void> mediumImpact();
+}
+
+/// Default implementation backed by Flutter's platform haptics.
+class FlutterHaptics implements Haptics {
+  const FlutterHaptics();
+
+  @override
+  Future<void> selectionClick() =>
+      _ignoreUnavailable(HapticFeedback.selectionClick);
+
+  @override
+  Future<void> lightImpact() => _ignoreUnavailable(HapticFeedback.lightImpact);
+
+  @override
+  Future<void> mediumImpact() =>
+      _ignoreUnavailable(HapticFeedback.mediumImpact);
+
+  Future<void> _ignoreUnavailable(Future<void> Function() feedback) async {
+    try {
+      await feedback();
+    } catch (_) {
+      // Haptics are optional and may be unavailable on the target device.
+    }
+  }
+}

lib/core/widgets/download_action.dart

@@ -1,10 +1,13 @@
 // Author: fruit.com.cn
 
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
 import '../../l10n/app_localizations.dart';
 import '../data/services/download_controller.dart';
+import '../platform/haptics.dart';
 import 'auth_gate.dart';
 
 /// 详情页与播放页共用的下载授权入口。
@@ -16,6 +19,7 @@ Future<void> requestEpisodeDownload(
 ) async {
   if (!await ensureSignedIn(context)) return;
   if (!context.mounted) return;
+  unawaited(context.read<Haptics>().lightImpact());
   final result = await context.read<DownloadController>().grant(episodeId);
   if (!context.mounted) return;
   final l10n = AppLocalizations.of(context)!;