feat(system-builder): three genre starters as data (4d3a)

[over2take]

As approved on 2026-10-09:

• Sword & Spell: d20 fantasy. Six abilities with floor((x - 10) / 2) modifiers, proficiency by level, unarmored defense, initiative, passive perception, gold pieces, vehicles and cyberware off, four NPC tiers whose HP is rolled for their level.
• Starfarer: 2d6 sci-fi. Six characteristics, every modifier read from one lookup table, a wound count (3, -1 each), three NPC tiers.
• Story First: narrative. Six approaches rated 0 to 3, harm levels, milestones, zones, no formulas; credited to Fate Accelerated Edition under CC BY 3.0.

Each entry in EXAMPLES now has a kind. GET /api/systems/examples lists the games as before; ?kind=starter lists the starters, and anything else is a 400. Copying a starter is POST /api/systems with { name, example } like a game.

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