Redact sensitive values in verbose command logging

[GrahamCampbell]

The spawn helper redacts sensitive-looking option values when it builds error messages, but the framework component's verbose log printed the full command line as-is. Since the arguments include --param entries built from component inputs, where environment-resolved values typically end up, a verbose run could echo secrets into retained CI logs.

The redaction logic now lives in its own redact-args util, required by both the spawn helper and the framework component, and the verbose log line passes its arguments through it before printing. Extracting the helper rather than exporting it from the spawn module keeps the existing test stubs of the spawn module working untouched, and the redaction behaviour itself is unchanged, including its existing limitation that only recognisably sensitive option names are matched. The real values still reach the spawned process exactly as before; only the log line differs.