feat(system-builder): CWN and SR6 as examples to copy (4d1a)

[over2take]

Cities Without Number and Shadowrun 6E as whole definitions in the builder's format: stats, labels, a sample character and setup answers around the parity-tested formulas in definitions.js, which they reuse word for word. Both check clean, so a copy is publishable as it stands, and their samples work out the same as the built-in recompute functions.

GET /api/systems/examples lists them, GET /api/systems/examples/:id opens one, and POST /api/systems with { name, example } copies one into a new draft. Main admin only, like every builder route. The built-in games keep their own code.

Summary

Test plan

• Tested locally
• Tests pass

Pre-merge checklist

Code quality:

• Code follows project style
• No breaking changes (or clearly documented)
• No console errors or warnings

Version & Release:

• Version bumped? If releasing to users, update:
  • frontend/package.json version
  • docker-compose.yml APP_VERSION
  • CHANGELOG.md with release notes
• GitHub Actions will auto-tag Docker images with the new version

Before merging to main:

• All tests passing
• PR reviewed and approved
• Branch is up to date with main
• No merge conflicts

Related issues