feat(store): introduce GitTokenStore for token persistence via Git backend

- Added `GitTokenStore` to handle token storage and metadata using Git as a backing storage.
- Implemented methods for initialization, save, retrieval, listing, and deletion of auth files.
- Updated `go.mod` and `go.sum` to include new dependencies for Git integration.
- Integrated support for Git-backed configuration via `GitTokenStore`.
- Updated server logic to clone, initialize, and manage configurations from Git repositories.
- Added helper functions for verifying and synchronizing configuration files.
- Improved error handling and contextual logging for Git operations.
- Modified Dockerfile to include `config.example.yaml` for initial setup.
- Added `gitCommitter` interface to handle Git-based commit and push operations.
- Configured `Watcher` to detect and leverage Git-backed token stores.
- Implemented `commitConfigAsync` and `commitAuthAsync` methods for asynchronous change synchronization.
- Enhanced `GitTokenStore` with `CommitPaths` method to support selective file commits.

Dockerfile

@@ -22,6 +22,8 @@ RUN mkdir /CLIProxyAPI
 
 COPY --from=builder ./app/CLIProxyAPI /CLIProxyAPI/CLIProxyAPI
 
+COPY config.example.yaml /CLIProxyAPI/config.example.yaml
+
 WORKDIR /CLIProxyAPI
 
 EXPOSE 8317