fix(player): 评论输入改为透明浮层并消除收起键盘抖动

lib/pages/player/widgets/drama_comments_sheet.dart

@@ -41,6 +41,7 @@ class DramaCommentsSheet extends StatefulWidget {
 class _DramaCommentsSheetState extends State<DramaCommentsSheet> {
   late final CommentRepository _comments;
   late final CommentController _controller;
+  OverlayEntry? _composerOverlay;
   OverlayEntry? _successOverlay;
   Timer? _successOverlayTimer;
   int? _serverCount;
@@ -61,6 +62,7 @@ class _DramaCommentsSheetState extends State<DramaCommentsSheet> {
 
   @override
   void dispose() {
+    _removeComposerOverlay();
     _successOverlayTimer?.cancel();
     _successOverlay?.remove();
     _controller.dispose();
@@ -86,20 +88,38 @@ class _DramaCommentsSheetState extends State<DramaCommentsSheet> {
   Future<void> _openComposer({DramaComment? replyTo}) async {
     await ensureSignedIn(context);
     if (!mounted || !context.read<AuthController>().isSignedIn) return;
-    final published = await showModalBottomSheet<bool>(
-      context: context,
-      isScrollControlled: true,
-      isDismissible: true,
-      backgroundColor: Colors.transparent,
-      barrierColor: Colors.transparent,
-      showDragHandle: false,
-      builder: (_) =>
-          CommentComposerSheet(controller: _controller, replyTo: replyTo),
+    _removeComposerOverlay();
+    final entry = OverlayEntry(
+      builder: (_) => CommentComposerSheet(
+        controller: _controller,
+        replyTo: replyTo,
+        onDismiss: _closeComposer,
+        onPosted: _handleComposerPosted,
+      ),
     );
-    if (published == true && mounted) {
-      _showPostSuccess();
-      await _refreshCount();
+    setState(() => _composerOverlay = entry);
+    Overlay.of(context, rootOverlay: true).insert(entry);
+  }
+
+  void _handleComposerPosted() {
+    _closeComposer();
+    _showPostSuccess();
+    unawaited(_refreshCount());
+  }
+
+  void _closeComposer() {
+    if (!mounted) {
+      _removeComposerOverlay();
+      return;
     }
+    setState(_removeComposerOverlay);
+  }
+
+  void _removeComposerOverlay() {
+    final entry = _composerOverlay;
+    _composerOverlay = null;
+    if (entry?.mounted ?? false) entry!.remove();
+    FocusManager.instance.primaryFocus?.unfocus();
   }
 
   void _handleDismissLayerTap() {
@@ -133,7 +153,7 @@ class _DramaCommentsSheetState extends State<DramaCommentsSheet> {
   @override
   Widget build(BuildContext context) {
     final sheetHeight = _sheetHeight(context);
-    return Stack(
+    final content = Stack(
       fit: StackFit.expand,
       children: [
         Positioned.fill(
@@ -179,6 +199,13 @@ class _DramaCommentsSheetState extends State<DramaCommentsSheet> {
         ),
       ],
     );
+    return PopScope(
+      canPop: _composerOverlay == null,
+      onPopInvokedWithResult: (didPop, _) {
+        if (!didPop && _composerOverlay != null) _closeComposer();
+      },
+      child: content,
+    );
   }
 
   Widget _content(BuildContext context) {