Sync Upstream (sync-ups)

Purpose

Keep this fork up to date with the upstream Three.js game-skills repo without clobbering the fork's own work. The fork differs from upstream in three ways that make an ordinary git merge impossible:

1. No shared git history — this is a re-host, not a git fork.
2. Different layout — upstream keeps skills at skills/; this fork keeps them at plugins/skills/.
3. Local-only content — the fork adds 5 Phaser skills, genre/Phaser premium checklists, a plugins/ wrapper, install.ps1, etc. These must survive every sync untouched.

So the sync is content-based and path-mapped, driven by a baseline manifest that records exactly which upstream files were synced and at which commit.

What gets synced