# Pull Request Summary: Add SSH Transport Support

This PR implements SSH transport support in the `git-sync` project, allowing users to interact with repositories over SSH. The implementation includes a new transport mechanism and integrates error handling, testing, and documentation.

## Commit Stack:  
1. **`f44c0ccc`** `gitproto: extract transport interface and rename HTTPConn`  
2. **`ebfc0d98`** `gitproto: add SSH transport via per-RPC ssh exec`  
3. **`74a4cf49`** `syncer: warn that SSH stats and progress are incomplete`  
4. **`c0b12714`** `tests: add end-to-end SSH transport coverage`  
5. **`98ca4e96`** `docs: document SSH support and caveats`  
6. **`3cc55f83`** `lint: fix transport linter findings`  
7. **`9c50a33f`** `ssh: clean up failed info-refs startup`

## Key Features:
- **SSH Transport Integration:** Added a new transport mechanism for SSH connections that supports `ssh://`, SCP-style `git@host:path.git`, and `git+ssh://` URLs.
- **Error Handling:** Ensures proper cleanup in case of failure, preventing leaked processes.
- **Warning for Incomplete Stats:** Introduced user-facing warnings for scenarios where byte-counted throughput is not available when using SSH.
- **Testing:** Comprehensive testing has been implemented, including unit tests for the SSH transport and end-to-end tests using a local shim.
- **Documentation:** Updates to the README and usage documentation to inform users about SSH support and its limitations.

## Remaining Caveat:
- The SSH implementation currently does not support byte-counted throughput statistics when using `--progress` and `--show-stats`. This limitation is documented in the warning messages.

## Action Items:
- Request review and merge.
- After merging, consider adding a follow-up PR for a more robust end-to-end test using Docker-based `sshd`.

For further details, please review the performance and coverage achieved by the end-to-end tests and unit tests included in this PR.