fix(recommend): 稳定进度拖动与清屏状态

lib/pages/recommend/recommend_page.dart

@@ -44,6 +44,7 @@ class RecommendPage extends StatefulWidget {
 class _RecommendPageState extends State<RecommendPage> {
   RecommendInnerTab _tab = RecommendInnerTab.feed;
   bool _scrubbing = false;
+  int _scrubCancelRequest = 0;
 
   @override
   Widget build(BuildContext context) {
@@ -80,21 +81,40 @@ class _RecommendPageState extends State<RecommendPage> {
               ),
             ),
           ),
-          if (!_scrubbing)
-            Positioned(
-              top: 0,
-              left: 0,
-              right: 0,
-              child: SafeArea(
-                bottom: false,
-                child: RecommendTopNav(
-                  selected: _tab,
-                  onVideo: _tab == RecommendInnerTab.feed,
-                  onSelected: (tab) => setState(() => _tab = tab),
-                  onSearch: widget.onSearch,
+          Positioned(
+            top: 0,
+            left: 0,
+            right: 0,
+            child: IgnorePointer(
+              child: SizedBox(
+                height: 72,
+                child: DecoratedBox(
+                  key: const Key('recommend-top-gradient'),
+                  decoration: const BoxDecoration(
+                    gradient: LinearGradient(
+                      begin: Alignment.topCenter,
+                      end: Alignment.bottomCenter,
+                      colors: [AppColors.mediaBlack, AppColors.transparent],
+                    ),
+                  ),
                 ),
               ),
             ),
+          ),
+          Positioned(
+            top: 0,
+            left: 0,
+            right: 0,
+            child: SafeArea(
+              bottom: false,
+              child: RecommendTopNav(
+                selected: _tab,
+                onVideo: _tab == RecommendInnerTab.feed,
+                onSelected: _selectTab,
+                onSearch: _handleSearch,
+              ),
+            ),
+          ),
         ],
       ),
     );
@@ -141,9 +161,31 @@ class _RecommendPageState extends State<RecommendPage> {
       onRefreshFeed: widget.feedController.refreshCurrent,
       onLoadMore: widget.feedController.loadMore,
       onScrubVisibilityChanged: _setScrubbing,
+      scrubCancelRequest: _scrubCancelRequest,
     );
   }
 
+  void _selectTab(RecommendInnerTab tab) {
+    final wasScrubbing = _scrubbing;
+    setState(() {
+      _tab = tab;
+      if (wasScrubbing) _scrubCancelRequest++;
+      _scrubbing = false;
+    });
+    if (wasScrubbing) widget.onScrubVisibilityChanged(false);
+  }
+
+  void _handleSearch() {
+    if (_scrubbing) {
+      setState(() {
+        _scrubbing = false;
+        _scrubCancelRequest++;
+      });
+      widget.onScrubVisibilityChanged(false);
+    }
+    widget.onSearch();
+  }
+
   void _setScrubbing(bool value) {
     if (_scrubbing == value) return;
     setState(() => _scrubbing = value);