Playable GameScene with basic visuals

[JakeyMarsh1]

As a player, I want a playable game scene with clear, minimal visuals so that I can move, see forward motion, and understand obstacles and goals.

Acceptance Criteria:

• GameScene initializes without errors and shows a readable layout: player, background, platforms, hazards, and candy are visually distinct using simple sprites or solid-color shapes.
• Player can move up/down; world motion is visible at a constant speed; collisions with platforms, hazards, and candy behave as designed (stand, lose, collect).
• Scene transitions are reliable: Menu → GameScene → GameOver (on hazard hit), with Restart returning to a fresh GameScene.
• Performance is smooth on the target machine; no duplicate listeners or overlapping scene instances after restart.

Tasks:

• Create GameScene.js with init/create/update; spawn player at start position; implement world motion (camera or scrolling background).
• Add placeholder visuals: simple background, player, platforms, hazards, and candy with distinct colors or minimal sprites; ensure legibility at gameplay speed.
• Configure physics: groups for platforms/hazards/candy; colliders and overlaps wired to stand/lose/collect behaviors.
• Wire transitions: Menu → GameScene; hazard collision → GameOver; GameOver Restart → fresh GameScene.
• Quick test pass: verify movement, motion, stand on platforms, game over on hazard, collect increments score, visuals are distinguishable, and restarts are clean.