✨ feat(revu): add implement skill for applying review comments

[kud]

Description

Adds the implement skill to the revu plugin — the execution-phase counterpart to the existing discuss skill. This completes the revu review loop:

• discuss → talks a review through interactively
• implement → reads the export, presents a checklist, confirms, then applies every comment exactly as written

The skill reads from .revu.json (preferred, structured) or revu-review.md (fallback annotated diff), groups comments by file into a numbered TODO checklist, gates behind an explicit yes/no confirmation, applies changes file-by-file without scope creep, then offers to delete the export and optionally run lint/tests.

It is self-contained and has no dependency on private agents — portable to any Claude Code setup that has the revu plugin.

This skill was previously living in the personal my repo as k-notes-implement, co-located with unrelated tooling. Moving it here puts it next to the review tooling it belongs to and makes it available to anyone using the plugin.

Screencast

No visual changes.

How to Validate

1. Check out feat/revu-implement-skill and install the revu plugin.
2. In a project directory, drop a .revu.json with a comments array (file, startLine, endLine, text fields).
3. Run the implement skill — verify it displays the numbered checklist grouped by file and does not touch any code yet.
4. Confirm with "yes" — verify it applies exactly the changes described, no more.
5. Verify it offers to delete the export only after all comments are processed.
6. Repeat with a revu-review.md to confirm the fallback path works.
7. Verify that if neither file is present, the skill stops with a clear message.

Developer Checklist

• Code is readable and maintainable
• PR is atomic and focused on a single feature
• Commits follow Conventional Commits
• Tests included and passing (if applicable)