feat(system-builder): STATS & RULES page, stats and tables (4b2d1)

[over2take]

components/StatsRulesPage.tsx, from the approved mockup builder-stats-rules (2026-10-06), tabs STATS and TABLES (FORMULAS follows in 4b2d2):

• STATS: a section per group (name, REMOVE GROUP), a row per stat with name, @id, lowest and highest (blank = none, whole numbers), TIED TO (any other stat), SAMPLE (blank clears it) and remove; + STAT, + GROUP.
• TABLES: name and id(), "up to / gives" rows with the last catching everything higher,
  • ROW and remove (not the last), TRY IT with the table's answer, + TABLE, REMOVE TABLE.

BuilderScreen shows it on STATS & RULES.

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