- Extend bonus items spritesheet from 9 to 12 frames (add flour + 2 firework objects)
- Add `flour` type to BONUS_ITEM config with warm off-white/tan color palette and firework variant (2-3x scale, half opacity for dust cloud effect)
- Implement per-type firework variants in BonusItemManager._explode() - particles can now have varied sizes and alpha while maintaining standard physics body size
- Add flour SFX asset (bonus-flour.mp3) and preload it
- Update editor to support placing flour bonus items with appropriate icon, color, and sprite frame
- Update all documentation (README, sprites.md) to reflect the new bonus item type
Additionally:
- Add campaign 2 bus physics customization: grippier tires (higher friction coefficients) and stiffer/less-damped suspension for bouncier ride
- Thread per-campaign wheel friction and suspension parameters through Bus entity from themes.js
- Redesign level11 with shorter course, fewer kids (4 vs 3), tighter time limit (42s vs 119s), and flour bonus items replacing most cash/CTC/guitar
