Bug: Use `RIPGREP_CONFIG_PATH` to determine config file of ripgrep in order to protect it

`.ripgreprc` is listed as special file which shall be protected from changes: https://github.com/anthropic-experimental/sandbox-runtime/blob/20f5176a94314038695bee13779eb9eebbbaeb49/src/sandbox/sandbox-utils.ts#L7-L21

The [documentation of ripgrep](https://iepathos.github.io/ripgrep/configuration-file/) states:

> ripgrep **does not** automatically look for configuration files in predetermined locations. Instead, you must explicitly tell ripgrep where to find your configuration file using the `RIPGREP_CONFIG_PATH` environment variable.

See also [Guide.md](https://github.com/BurntSushi/ripgrep/blob/master/GUIDE.md#configuration-file) from ripgrep. Thus the config file can be anywhere on the computer (for example in `.config/ripgrep/ripgreprc`). Thus in my understand `str` should use the `RIPGREP_CONFIG_PATH` env variable to determine the file which needs protection.