feat(api): use Tencent 16k_zh_large ASR and remove local Whisper

Standardize ASR on Tencent's dialect-capable engine across all environments,
drop faster-whisper from dependencies and deployment images, and add an
expo-sqlite iOS vendor sync plus pod install in prebuild to prevent native
build failures after npm install.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -64,7 +64,6 @@ dist/
 *.egg-info/
 app-expo/coverage/
 
-# 本地 ASR 模型缓存（Whisper 每次启动从该目录加载）
 api/models/certs/
 api/models/whisper/