Search file contents with a regex under ctx.cwd.
Shells out to rg (ripgrep) when available for speed + sanity; falls back
to a pure-Elixir scan using Path.wildcard + File.read when not.
Arguments:
pattern(required) — regex.path_glob(optional) — restrict the scan to files matching this glob.max_results(optional, default 200) — cap on matching lines returned.