Offer PII redaction during entire enable

PII redaction is opt-in under redaction.pii and nothing in setup mentioned it, so users had to find the setting on their own.

The first interactive entire enable now asks "Redact personal info from saved transcripts?" after the telemetry question. The default is No, and declining writes nothing. A new --redact-pii flag on enable and configure turns it on (or off with =false) without the prompt. --yes and runs without a terminal never ask.

On a configured repo, enable --redact-pii writes the setting alongside the strategy and backend flags instead of opening agent management, which writes no settings.