Cover all six pathological character classes (single-quote,
double-quote, space, semicolon, newline, backtick) in both
upstream URL and name positions. Each case validates rendered
output via `sh -n` and asserts the original value is preserved
verbatim after shlex.quote encoding. Also add `sh -n` smoke
tests for the static pre-receive and access-hook scripts.
Use shlex.quote() on name and upstream_url in git_gate_render_entrypoint()
so special characters (single quotes, spaces, semicolons) cannot break or
inject into the generated sh script.
Add _GIT_NAME_RE validation in GitEntry.from_repos_entry() to restrict
repo names to [A-Za-z0-9._-]+, making the manifest the first line of
defence and shlex.quote() the belt-and-suspenders backstop.
Closes#155
didericis-claude