chore(agricola): update state

[github-actions]

Important

This pull request is maintained by automation. Merge it to checkpoint state on the default branch; do not close or edit it manually.

Motivation

Persist Agricola's durable cursor and decision ledger through the repository's required pull-request path.

Summary

• tracks the latest processed canonical merge
• records immutable source snapshots and maintainer decisions

Key design considerations

• workflow code always executes from the protected default branch
• this pull request is updated in place as state advances

[claude]

LGTM. This is an automated state checkpoint that only touches data under ledger/.

What was reviewed:

• Per-PR ledger files for mppx PRs 774 through 1053. In each one, the id, source.repo and source.pr match the filename. Each idempotency_key (in #774 and #784) follows the pattern propagate:mppx#N:target.
• The cursor moves forward to 2026-10-15T23:00:08Z, and the new audit.json is append-style finding records.
• #915 has a label but no decisions yet. I ruled this out as a problem: per the agricola README, decisions are added later through the tracking issue.

Extended reasoning...

The change adds or updates 194 JSON files under ledger/: the cursor, a new audit findings list, and per-PR snapshot files for wevm/mppx. It has no code or workflow changes. It touches no security-sensitive surface. The executable control-plane code runs from the protected default branch, so this PR only checkpoints data. I approved because the data is mechanical and internally consistent, with ids, PR numbers and idempotency keys matching. There are also no CODEOWNERS files and no open reviewer objections.