7bcbbc7d1a
- Added `_require_fetch_ref` validator to enforce strict alphanumeric character sets and disallow special git characters (e.g., `:`, `--`, `..`, `*`). - Integrated validation into `git_fetch_ref_endpoint` to block malicious refspec inputs before git execution. - Added test cases in `test_proxy_server.py` to verify rejection of attempted shell and refspec injections.