feat: WebView/媒体/红包详情全量实现 (#25~#30)

#25 MiniAppWebViewPage + MiniAppRouter
  - webview_flutter 加载 {apiBaseUrl}/miniapp/{appId}/index.html?gameId=...&token=...
  - MiniAppFloatButton 接收 chatId/chatType，默认打开 WebView
  - BannerState 新增 appId 字段，由 GameBannerData.appId 填充

#26 open_filex 文件打开
  - FileMessageBubble 下载完成后调用 OpenFilex.open(localPath)
  - 打开失败时 SnackBar 提示

#27 audioplayers 音频播放
  - AudioPlaybackService(Notifier)：单例 AudioPlayer，togglePlay/pause/seek
  - AudioMessageBubble 接入：播放态图标切换、进度 mm:ss 显示

#28 video_player + chewie 视频全屏
  - VideoPlayerPage：本地文件 / HTTP 双模，chewie 控制栏
  - VideoMessageBubble 默认 onTap → push VideoPlayerPage

#29 红包领取排行榜详情页
  - GET /payment/rp/detail → RpDetailData + RpRecordItem DTO
  - GetRpDetailUseCase + getRpDetailUseCaseProvider
  - RedEnvelopeDetailSheet：汇总行 + 领取排行列表，头像/昵称/金额/时间

#30 MINE_RP 地雷红包发包 UI
  - _RpType 新增 mine(MINE_RP)，显示地雷金额输入框
  - SendRpRequest.parameters 携带 mineAmount
  - RedEnvelopeBubble：非活跃状态直接打开详情，活跃状态领取后打开排行榜

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/im_app/lib/features/chat/presentation/banner_view_model.dart

@@ -10,6 +10,8 @@ import 'package:im_app/features/chat/di/red_envelope_provider.dart';
 class BannerState {
   final String gameId;
   final String gameName;
+  /// 小程序 appId（用于 WebView URL 构造）
+  final String appId;
   final String? lastResult;
   final BannerGameStatus status;
   final int countdownSeconds;
@@ -19,6 +21,7 @@ class BannerState {
   const BannerState({
     this.gameId = '',
     this.gameName = '',
+    this.appId = '',
     this.lastResult,
     this.status = BannerGameStatus.idle,
     this.countdownSeconds = 0,
@@ -29,6 +32,7 @@ class BannerState {
   BannerState copyWith({
     String? gameId,
     String? gameName,
+    String? appId,
     String? lastResult,
     BannerGameStatus? status,
     int? countdownSeconds,
@@ -38,6 +42,7 @@ class BannerState {
     return BannerState(
       gameId: gameId ?? this.gameId,
       gameName: gameName ?? this.gameName,
+      appId: appId ?? this.appId,
       lastResult: lastResult ?? this.lastResult,
       status: status ?? this.status,
       countdownSeconds: countdownSeconds ?? this.countdownSeconds,
@@ -139,6 +144,7 @@ class BannerViewModel extends Notifier<BannerState> {
     state = state.copyWith(
       gameId: bean.gameId.isNotEmpty ? bean.gameId : state.gameId,
       gameName: bean.gameName.isNotEmpty ? bean.gameName : state.gameName,
+      appId: (bean.appId != null && bean.appId!.isNotEmpty) ? bean.appId : state.appId,
       lastResult: lastResult,
       status: isOpen ? BannerGameStatus.open : BannerGameStatus.close,
       countdownSeconds: countdown,