feat: add Goo Tower game with physics engine, 12 levels, and editor
Implement Waves 0-3 of Goo Tower, a World of Goo-inspired physics
puzzle game. Includes:
- GooTowerLogic.js: Verlet integration with XPBD constraints, terrain
collision, ball-ball collision, strand breaking, crawling agents,
and 9 goo types (common, ivy, balloon, bomb, block, pokey, bit,
skull, anchor)
- GooTowerGame.js: Phaser scene with procedural rendering, drag-and-
drop placement, pipe collection, and win/OCD tracking
- GooTowerEditor.js: Level editor (/?gootower-editor=1) with terrain
drawing, ball/pile placement, settle/test/export tools
- 12 hand-tuned levels across 2 chapters (teaching + sandbox)
- verifyGooTower.js: 303-check regression harness
- genGooTower.js: Level bank writer
- GooTowerAuto.js: Greedy reference player (winnability gate)
- Wiring into gamesRegistry, main.js, GameRoomScene, and PreloadScene
