## Summary
This PR tightens repository quality enforcement around markdown and documentation. It adds `markdownlint` to the `cicd-checks` workflow, expands pre-commit coverage so markdown files are checked repo-wide, and cleans up the PP-58 documentation set to keep it aligned with the new policy.
## What changed
- Added a `Markdownlint Check` entry to `.gitea/workflows/cicd-checks.yaml`
- Added `markdownlint` to pre-commit and widened prettier coverage to include markdown files across the repo
- Updated `README.md` to satisfy markdownlint line-length rules
- Normalized the PP-58 documentation set:
- `docs/DEPLOYABLE_RUNTIME_CONTRACT.md`
- `docs/adr/ADR003-deployable_runtime_image_contract.md`
- `docs/DEVELOPMENT.md`
- `docs/CICD_MULTI_STAGE_BUILD.md`
- `docs/CICD_TROUBLESHOOTING_GUIDE.md`
- `docs/SECURE_DOCKER_CICD.md`
## Validation
- `pre-commit run markdownlint --files README.md docs/DEPLOYABLE_RUNTIME_CONTRACT.md`
- `pre-commit run prettier --files README.md docs/DEPLOYABLE_RUNTIME_CONTRACT.md`
- Workflow YAML validation returned no errors
## Notes
This change does not alter application runtime behavior. It only strengthens CI and documentation quality enforcement.
Co-authored-by: copilotcoder <copilotcoder@darkhelm.org>
Reviewed-on: #68
