Add resolution comment to issues after PR merge

[sebastientaggart]

After a PR merges via /submit-for-review, the linked GitHub issue now receives a plain-language "Resolution" comment summarizing what was done. This gives PMs and BAs a self-contained view of the ticket without needing to read PR diffs.

The new step sits in the post-merge flow between QA label application and the success report. It reads the original issue body, writes a 1-3 sentence non-technical summary, and references the PR for anyone who wants full details.

Issue #93

[sebastientaggart]

Review Summary

Verdict: APPROVE

Findings

No issues found. Code looks correct and follows project conventions.

The new resolution comment step is inserted in the right place in the post-merge flow (after QA label, before success report), is consistently applied across all 5 adapter files and the source template, and the gh issue comment invocation follows the existing heredoc pattern used elsewhere in the skill. The "skip silently if no linked issue" guard matches the convention used by the QA label step above it. Not wrapping the block in branch-conditional guards is correct since a resolution comment is useful regardless of branch strategy.