fix(vad): bundle local Silero model

[问题原因]
- 先前实现会在包内权重缺失时读取外部 faster-whisper 资源，无法满足自包含部署要求。

[问题根因]
- 项目包中尚未包含已验证的 ONNX 权重，VAD 路径保留了开发期回退逻辑。

[修复方案]
- 提交已校验 SHA-256 的本地 Silero ONNX 权重并移除外部包回退。
- 增加模型打包和缺失模型失败路径测试，并更新来源、MIT 许可和哈希说明。

[影响范围]
- VAD 现在只加载项目包内模型，不联网且不依赖 faster-whisper 运行时资源。
- 未安装、启用或启动任何用户 systemd 服务。

1 files changed, 8 insertions, 6 deletions

diff --git a/THIRD_PARTY_NOTICES.md b/THIRD_PARTY_NOTICES.md
index e38fc8e..e147b4e 100644
--- a/THIRD_PARTY_NOTICES.md
+++ b/THIRD_PARTY_NOTICES.md
@@ -2,12 +2,14 @@
 
 ## Silero VAD ONNX weight
 
-The intended bundled file is `src/mic_clipper/assets/silero_vad_v6.onnx`.
+The bundled file is `src/mic_clipper/assets/silero_vad_v6.onnx`.
 
-Its local source is the `assets/silero_vad_v6.onnx` file in the verified
-`faster-whisper` 1.2.1 installation. That package's installed metadata declares
-the MIT license and its VAD implementation attributes the model integration to
+It was copied from `assets/silero_vad_v6.onnx` in the locally verified
+`faster-whisper` 1.2.1 installation. Both files have SHA-256
+`4cbf549b8326f60f80f2536d9eefeb450a9abe83365a098031c89719f1be17d2`.
+The installed package metadata declares the MIT license, and its VAD
+implementation attributes the model integration to
 [`snakers4/silero-vad`](https://github.com/snakers4/silero-vad).
 
-The ONNX weight has no network retrieval path in this project. The asset must be
-present before deployment; it is intentionally not downloaded at runtime.
+The ONNX weight is bundled and has no network retrieval path. The application
+never downloads models at runtime.