refactor(config): 七牛/微信密钥外置——AK/SK+微信AppID 入本地 app_config, domain/bucket 走远程配置

- app_config.json + AppConfig: qiniu_access_key/qiniu_secret_key/wechat_app_id/wechat_app_secret(扁平snake_case)
- RemoteConfig.VersionFields + audio_domain/audio_bucket(4层可携带), VersionDecision + audioDomain/audioBucket
- VersionResolver.resolve 复用 pickStr 解析 audioDomain/audioBucket(4层逐级回退)
- QiniuToken.uploadToken(accessKey,secretKey,bucket) 改传参,去掉硬编码常量
- AudioProvider.doUpload: AK/SK取本地配置, domain/bucket取远程配置(cfg.resolve), URL用远程domain
- WeChatApi.configure(appId) 注入AppID(去WX_APP_ID常量), EntryAbility.onCreate 从配置注入
- 更新 QiniuToken 单测传参

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

feature_capabilities/Index.ets

@@ -23,7 +23,7 @@ export { AmrRecorder } from './src/main/ets/providers/AmrRecorder';
 export { NavProvider } from './src/main/ets/providers/NavProvider';
 
 // 微信 SDK 封装（EntryAbility 处理回调 want 需用）
-export { WeChatApi, WX_APP_ID } from './src/main/ets/wx/WeChatApi';
+export { WeChatApi } from './src/main/ets/wx/WeChatApi';
 
 // 分享文本拼接纯函数（供单测）
 export { buildShareText } from './src/main/ets/share/ShareText';