feat(home): 顶部导航随翻页联动并把推荐更名为精选

lib/pages/recommend/home_tab_motion_controller.dart

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+// Author: fruit.com.cn
+// 职责：协调首页三页的点击动画、最终选中目标和手势中断。
+import 'package:flutter/widgets.dart';
+
+const _transitionDuration = Duration(milliseconds: 220);
+
+/// 页面移动时保留用户最终目标，防止跨页动画途中的页面抢占高亮。
+class HomeTabMotionController extends PageController {
+  /// [onSettled] 在动画结束或被手势中断时同步实际停留页面。
+  HomeTabMotionController({required this.onSettled});
+
+  final ValueChanged<int> onSettled;
+  int? _target;
+  int _revision = 0;
+  bool _disposed = false;
+
+  /// 供导航绘制连续位置；布局尚未建立时使用初始页。
+  double get pagePosition => hasClients && position.hasContentDimensions
+      ? page ?? initialPage.toDouble()
+      : initialPage.toDouble();
+
+  /// 点击跨页过程中只接受最终目标；拖动和稳定状态接受实际页。
+  bool acceptsSelection(int index) => _target == null || _target == index;
+
+  /// 点击导航时平滑移动；系统减少动画时直接到位。
+  Future<void> selectPage(int index, {required bool reduceMotion}) async {
+    final revision = ++_revision;
+    _target = index;
+    if (!hasClients) {
+      _target = null;
+      return;
+    }
+    if (reduceMotion) {
+      jumpToPage(index);
+    } else {
+      await animateToPage(
+        index,
+        duration: _transitionDuration,
+        curve: Curves.easeOut,
+      );
+    }
+    if (_disposed || revision != _revision) return;
+    _target = null;
+    if (hasClients) onSettled(pagePosition.round());
+  }
+
+  @override
+  void dispose() {
+    _disposed = true;
+    super.dispose();
+  }
+}