Sprint 0: bug fixes and cleanup

- Fix Rocket/PropellerHat hitboxes (relative to sprite size, not magic offsets)
- Spring now destroys itself on use with squash animation instead of staying invisible
- Guard all powerups against double-trigger via consumed flag
- Save genesis glow tween reference for clean destroy
- Player.die() disables collisions (no more post-death platform bounces)
- Replace hardcoded enemy spawn cap 0.5 with DIFFICULTY.maxEnemyRate
- Enemy spawn position now anchored to platform X (-60/+60), not random
- Powerup spawn clamped to screen bounds
- Skip powerup spawn on breaking platforms (was unfair)
- ScoreManager.addPoints() public method; remove direct score mutation
- HUD elements use setScrollFactor(0) instead of per-frame repositioning
- All magic numbers extracted to SCORE / PHYSICS / POWERUP_DURATION config
- Remove dead code: showDeathVignette, drawDebug, createParticles, deathOverlay
- Remove dead constants: PLATFORM_WIDTH/HEIGHT, PLAYER_MAX_SPEED, tileBias
- Remove SUBMIT TO CHAIN fake button, replace with Coming Soon text
- Safer cleanup loop: collect-then-destroy instead of mutating during iterate
- gwei particles now have setScrollFactor(0.3) for parallax depth

src/main.js

@@ -1,9 +1,9 @@
-import { Game, AUTO } from 'phaser';
+import { Game, AUTO, Scale } from 'phaser';
 import { BootScene } from './scenes/BootScene.js';
 import { MenuScene } from './scenes/MenuScene.js';
 import { GameScene } from './scenes/GameScene.js';
 import { GameOverScene } from './scenes/GameOverScene.js';
-import { GAME_WIDTH, GAME_HEIGHT } from './config/game.config.js';
+import { GAME_WIDTH, GAME_HEIGHT, GRAVITY } from './config/game.config.js';
 
 const config = {
   type: AUTO,
@@ -12,15 +12,14 @@ const config = {
   height: GAME_HEIGHT,
   backgroundColor: '#0d001a',
   scale: {
-    mode: Phaser.Scale.FIT,
-    autoCenter: Phaser.Scale.CENTER_BOTH,
+    mode: Scale.FIT,
+    autoCenter: Scale.CENTER_BOTH,
   },
   physics: {
     default: 'arcade',
     arcade: {
-      gravity: { y: 1200 },
+      gravity: { y: GRAVITY },
       debug: false,
-      tileBias: 64,
     },
   },
   scene: [BootScene, MenuScene, GameScene, GameOverScene],