Only generate the post-merge test plan for PRs labeled 'PR : dotbot review'

[erickgonzalez]

Description

The Claude AI Post-Merge Test Plan workflow (.github/workflows/ai_claude-post-merge-test-plan.yml) currently generates a QA test plan for every merged PR that carries Area : Backend or Area : Frontend. It should be opt-in: only PRs that carry the PR : dotbot review label (the same label that already triggers the dotbot AI code review) should get a plan after merge.

A manual workflow_dispatch run should keep working without the label, since dispatching by hand is already an explicit request and is the way to plan a PR that got the label only after it merged.

Acceptance Criteria

• A merged PR with PR : dotbot review and an Area label gets a test plan.
• A merged PR with an Area label but without PR : dotbot review is skipped, with a notice in the preflight log.
• A merged PR with PR : dotbot review but no Area label is still skipped.
• A manual dispatch against a merged PR with an Area label runs even without PR : dotbot review.
• The PR : dotbot review label description mentions that it also triggers the post-merge test plan.

Priority

Medium

[github-actions]

PRs linked to this issue

• docs(test-plan): describe the dotbot opt-in the workflow now requires by @erickgonzalez