:sig
String runtime_safe_key(String key, String label = "runtime key")

:params
key : caller-provided key
label : diagnostic label used by native error handling
return value : stable SHA-1 key, or an empty string for empty input in wasm

:see
>sys
>gen_sha1

:content
Trims a runtime key and converts it to a stable SHA-1 identifier suitable for task/runtime file names.

:example
print(runtime_safe_key("  My Task Name  "), "\n");
