Port .gitea/pull_request_template.md to .gitlab/merge_request_templates/
Default.md so new GitLab MRs surface the same structured prompt once
Phase 2 lands the pipeline and developers start opening MRs.
Two content adjustments vs the Gitea original:
- PR -> MR in the comment header (GitLab terminology).
- Fixed a stale ref to docs/development.md "section 5" (Observability
dev-loop); the Conventional Commits convention is in section 7.
Phase 1 ships repo-side artefacts only; ops bootstrap (mirror push,
groups, branch protection, bot signing keys, Renovate endpoint
reconfig) happens on vm-gitlab outside this PR per ADR-0028
section 'Migration sequence'.
Julien Gautier