Integrate review-fix loop into draft-first workflow

[costajohnt]

Problem

During the nickel-lang/nickel#2529 PR workflow, the code review loop was not part of the standard workflow. The user had to explicitly request "use the pr-review-toolkit to review the PR and fix issues in a loop until they converge."

The review caught real issues (flag naming, missing manual update, terse help text) that should have been caught automatically before the PR was marked ready.

Proposal

Add a review-fix-converge loop as a standard step in the draft-first workflow:

1. After creating the draft PR, automatically run a code review
2. Fix any issues found
3. Re-review until no issues remain
4. Only then proceed to mark the PR ready

This prevents shipping reviewable issues to maintainers and reduces review round-trips.

[costajohnt]

This is already implemented in the draft-first workflow. Step 2 (Draft PR Review Cycle) in workflows/draft-first-workflow.md automatically:

1. Dispatches 5+ review agents after creating the draft PR
2. Consolidates findings (Critical/Recommended/Minor)
3. Offers "Address findings" which fixes issues, commits, pushes, and loops back for re-review
4. Has a soft limit after 3 rounds to suggest finalizing
5. Only proceeds to Step 3 (integration check) when review converges

The full review-fix-converge loop is already a standard part of the workflow — no additional changes needed.