Always include a Paperclip issue link in every GitHub PR description.

Why: User feedback on 2026-03-19 via TEC-7 comment: “Ensure PRs include a link!” — the board needs traceability from PR → issue.

How to apply: At PR creation time, append to the PR body:

---

Paperclip issue: [TEC-XX](https://paperclip.lab.ctoaas.co/TEC/issues/TEC-XX)

Derive the prefix from the issue identifier (e.g. TEC-7 → prefix TEC). The Paperclip public URL is https://paperclip.lab.ctoaas.co.