媒体预览优化与视频播放器功能增强

// 原代码 - image_preview_page.dart
isLoading: _loadingStates[_imageFiles[index].id] ?? true,

// 修复后
final file = _imageFiles[index];
final isLoading = _loadingStates[file.id] == true && !_imageCache.containsKey(file.id);

fullscreen: MaterialVideoControlsThemeData(
  // 原有配置
  padding: const EdgeInsets.symmetric(horizontal: 16),
  // 新增配置
  topButtonBarMargin: const EdgeInsets.fromLTRB(16, 16, 16, 0),
  bottomButtonBarMargin: const EdgeInsets.fromLTRB(16, 0, 16, 16),
),

// 原代码 - chat_page.dart
Expanded(
  child: _isVoiceMode
      ? _buildVoiceRecordButton(...)  // 固定高度
      : _buildTextInputArea(...),      // 可变高度 (minLines: 1, maxLines: 4)
),

Expanded(
  child: AnimatedSwitcher(
    duration: const Duration(milliseconds: 200),
    transitionBuilder: (child, animation) {
      return FadeTransition(opacity: animation, child: child);
    },
    child: _isVoiceMode
        ? KeyedSubtree(
            key: const ValueKey('voice'),
            child: _buildVoiceRecordButton(...),
          )
        : KeyedSubtree(
            key: const ValueKey('text'),
            child: _buildTextInputArea(...),
          ),
  ),
),

// 状态变量
bool _isLongPressing = false;
double _speedBeforeLongPress = 1.0;
static const double _longPressSpeed = 2.0;
 
// 长按开始
void _onLongPressStart() {
  if (_isLocked) return;  // 锁定时不响应
  _speedBeforeLongPress = _currentSpeed;  // 保存当前速度
  _player.setRate(_longPressSpeed);       // 切换到加速
  setState(() => _isLongPressing = true);
}
 
// 长按结束
void _onLongPressEnd() {
  if (!_isLongPressing) return;
  _player.setRate(_speedBeforeLongPress);  // 恢复原速度
  setState(() => _isLongPressing = false);
}

GestureDetector(
  onLongPressStart: (_) => _onLongPressStart(),
  onLongPressEnd: (_) => _onLongPressEnd(),
  onLongPressCancel: _onLongPressEnd,  // 取消时也要恢复
  child: MaterialVideoControlsTheme(...),
)

if (_isLongPressing)
  Positioned(
    top: 80,
    left: 0,
    right: 0,
    child: Center(
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
        decoration: BoxDecoration(
          color: Colors.black87,
          borderRadius: BorderRadius.circular(20),
        ),
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(TablerIcons.player_play, color: Colors.white, size: 18),
            SizedBox(width: 6),
            Text('${_longPressSpeed}x 加速中', style: TextStyle(color: Colors.white)),
          ],
        ),
      ),
    ),
  ),

bool _isLocked = false;
 
void _toggleLock() {
  setState(() => _isLocked = !_isLocked);
  if (_isLocked) {
    showAppToast(context, '已锁定，点击锁图标解锁');
  }
}

MaterialVideoControlsThemeData(
  // 锁定时禁用所有手势
  seekOnDoubleTap: !_isLocked,
  seekGesture: !_isLocked,
  volumeGesture: !_isLocked,
  brightnessGesture: !_isLocked,
  // 锁定时隐藏底部控件
  bottomButtonBar: _isLocked ? [] : const [...],
)

MaterialCustomButton(
  onPressed: _toggleLock,
  icon: Icon(
    _isLocked ? TablerIcons.lock : TablerIcons.lock_open,
    color: _isLocked ? Colors.orange : Colors.white,
  ),
),

if (_isLocked)
  Positioned(
    bottom: 80,
    left: 0,
    right: 0,
    child: Center(
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
        decoration: BoxDecoration(
          color: Colors.black54,
          borderRadius: BorderRadius.circular(16),
        ),
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(TablerIcons.lock, color: Colors.orange, size: 16),
            SizedBox(width: 4),
            Text('已锁定', style: TextStyle(color: Colors.white70, fontSize: 12)),
          ],
        ),
      ),
    ),
  ),

<!-- 修改前 -->
<application android:label="E2E Pan" ...>
 
<!-- 修改后 -->
<application android:label="AgentIO" ...>

// 修改前
if (!window.Create(L"e2eepan_client", origin, size)) {
 
// 修改后
if (!window.Create(L"AgentIO", origin, size)) {

// 修改前
itemBuilder: (context, index) {
  return _ImageViewerItem(
    file: _imageFiles[index],
    imageData: _imageCache[_imageFiles[index].id],
    isLoading: _loadingStates[_imageFiles[index].id] ?? true,  // 问题所在
    ...
  );
},
 
// 修改后
itemBuilder: (context, index) {
  final file = _imageFiles[index];
  // 只有在明确加载中时才显示 loading，否则检查缓存
  final isLoading = _loadingStates[file.id] == true && !_imageCache.containsKey(file.id);
  return _ImageViewerItem(
    file: file,
    imageData: _imageCache[file.id],
    isLoading: isLoading,
    ...
  );
},

// 长按加速相关
bool _isLongPressing = false;
double _speedBeforeLongPress = 1.0;
static const double _longPressSpeed = 2.0;
 
// 锁定屏幕相关
bool _isLocked = false;

return SafeArea(
  child: Stack(
    children: [
      // 视频播放器主体（包含 GestureDetector 和 MaterialVideoControlsTheme）
      Center(
        child: GestureDetector(
          onLongPressStart: (_) => _onLongPressStart(),
          onLongPressEnd: (_) => _onLongPressEnd(),
          onLongPressCancel: _onLongPressEnd,
          child: MaterialVideoControlsTheme(...),
        ),
      ),
      // 长按加速提示
      if (_isLongPressing) Positioned(...),
      // 锁定状态提示
      if (_isLocked) Positioned(...),
    ],
  ),
);