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>

api/tests/test_default_toml_legacy_parity.py

@@ -16,8 +16,7 @@ def test_default_toml_matches_legacy_settings_defaults() -> None:
 
     assert cfg.story.image_min_body_chars == 400
 
-    assert cfg.asr.provider == "whisper"
-    assert cfg.asr.device == "auto"
-    assert cfg.asr.compute_type == "auto"
+    assert cfg.asr.provider == "tencent"
+    assert cfg.asr.engine_type == "16k_zh_large"
 
     assert cfg.misc.tencent_sms_template_param_count == 2