ADR-0016: clarify or remove the confusing "Rollback" section #250

Context

Follow-up from the review of #241 (merged f1693aa). @mogul left an unresolved conversation on docs/adr/0016-kit-bundle-provenance-and-stale-refresh.md:150 (the Rollback section) and asked that we track it as an issue rather than block the merge.

His comment:

I'm really unclear on what "rollback" means in the context of an ADR's structure, though. Can you explain more? Is this about the ADR, or about the data it's talking about managing for provenance? When would a rollback be desirable/necessary? It just sticks out as unmoored to the actual feature.

The problem

The current section reads:

Rollback — Revert the commits on the feature branch. The provenance records under ~/.local/state/acq/provenance are inert data; they can be left in place or removed with no effect on sandboxes. No sandbox state is touched by a rollback.

It conflates two distinct ideas and isn't a standard MADR heading:

1. Reverting the code change (undo the feature) — a VCS action.
2. Cleaning up the provenance data the feature writes — an operational note about the host-side records.

Neither is really "rollback" in the ADR-decision sense, and mixing them makes the section feel unmoored from the decision.

Proposed fix (pick one)

• A (preferred): Drop the standalone "Rollback" section. Fold the useful fact — "provenance records under ~/.local/state/acq/provenance are inert; deleting them only makes acq re-offer a refresh (safe/idempotent)" — into Consequences → Neutral. If a revert note is wanted, state it plainly under Consequences as "the feature can be reverted with no sandbox-state impact."
• B: Keep a short "Reversibility" note but split the two ideas explicitly (code revert vs. data cleanup) and tie each to why you'd do it.

Acceptance

• ADR-0016 no longer has an unmoored "Rollback" section; the reversibility/data-cleanup facts live where a reader expects them.
• Wording answers "what does rolling this back mean and when would you do it."

Non-blocking; docs-only. AI-assisted (OpenCode); requires human review.