pub fn resolve_external_tool(name: &str) -> Result<PathBuf>Expand description
Resolve an external (non-Greentic-channel) tool binary by its plain name.
Unlike resolve_binary, this never appends the toolchain channel suffix
(-dev/-rnd): external tools such as greentic-mcp-gen ship a single,
unsuffixed binary. Resolution order: GREENTIC_DEV_BIN_<NAME> env override,
then PATH.