feat(app): 完善播放协议搜索与空状态

test/player/seek_scrub_visibility_test.dart

@@ -154,12 +154,37 @@ void main() {
     await tester.pumpAndSettle();
   });
 
+  testWidgets('feed progress thumb stays on the finger when dragged right', (
+    tester,
+  ) async {
+    await _pumpFeedOverlay(tester);
+    final bar = find.byKey(const Key('home-feed-progress'));
+    final gesture = await tester.startGesture(tester.getCenter(bar));
+
+    await gesture.moveBy(const Offset(800, 0));
+    await tester.pump();
+
+    final thumbCenter = tester
+        .getRect(find.byKey(const Key('home-feed-progress-thumb')))
+        .center
+        .dx;
+    final playedRight = tester
+        .getRect(find.byKey(const Key('home-feed-progress-played')))
+        .right;
+    expect(thumbCenter, closeTo(tester.getRect(bar).right, 0.5));
+    expect(playedRight, closeTo(thumbCenter, 0.5));
+
+    await gesture.up();
+    await tester.pumpAndSettle();
+  });
+
   testWidgets('full player drag clears chrome and release restores it', (
     tester,
   ) async {
     await _pumpFullPlayerOverlay(tester);
     expect(find.byKey(const Key('player-controls-top')), findsOneWidget);
     expect(find.byKey(const Key('player-bottom-actions')), findsOneWidget);
+    final progressTop = tester.getTopLeft(find.byType(Slider)).dy;
 
     final gesture = await tester.startGesture(
       tester.getCenter(find.byKey(const Key('player-progress'))),
@@ -170,8 +195,9 @@ void main() {
     expect(_opacity(tester, const Key('player-controls-top')), 0);
     expect(_opacity(tester, const Key('player-interaction-rail')), 0);
     expect(_offstage(tester, const Key('player-controls-bottom')), isTrue);
-    expect(_offstage(tester, const Key('player-bottom-actions')), isTrue);
+    expect(_opacity(tester, const Key('player-bottom-actions')), 0);
     expect(find.byKey(const Key('player-progress')), findsOneWidget);
+    expect(tester.getTopLeft(find.byType(Slider)).dy, progressTop);
 
     await gesture.up();
     await tester.pumpAndSettle();
@@ -179,6 +205,7 @@ void main() {
     expect(_opacity(tester, const Key('player-controls-top')), 1);
     expect(_opacity(tester, const Key('player-interaction-rail')), 1);
     expect(_offstage(tester, const Key('player-bottom-actions')), isFalse);
+    expect(tester.getTopLeft(find.byType(Slider)).dy, progressTop);
   });
 }