Phase A: stability and performance

A1 Pooled particle system
- New ParticleManager owns 9 reusable Phaser emitters created once per scene
  (jump, explosion, powerup, puff, sparks, flame, wind, spring, speedline)
- BootScene generates reusable white textures (px_square/soft/streak/ring)
- GameScene burst helpers + EffectsManager flow effects now delegate to the
  pool instead of allocating rectangles + tweens every frame
- Quality auto-detect (low on mobile/small screens) cuts particle counts

A2 Fix high-speed landing tunneling
- Cap downward velocity at PHYSICS.maxFallSpeed (boosts unaffected)
- platformCollisionFilter now uses a swept deltaY one-way check so a fast
  fall can never be wrongly rejected or passed through

A3 Safe storage
- New utils/storage.js wraps localStorage with in-memory fallback so private
  mode / quota errors cannot crash the game; all access routed through it

A4-A6 Lifecycle and robustness
- Global error / unhandledrejection guard recovers to the menu
- GameScene auto-pauses on tab hidden and cleans up the cross-scene listener
  on shutdown; fps pacing + disableContextMenu in game config
- Moving platforms use a proper dynamic body instead of destroy()+new Body

Verified in-browser: menu + game load with zero console errors, all emitters
active, normal bouncing works, fall speed capped.

src/scenes/MenuScene.js

@@ -2,6 +2,7 @@ import { Scene } from 'phaser';
 import { sound } from '../managers/SoundManager.js';
 import { AchievementsManager } from '../managers/AchievementsManager.js';
 import { createButton } from '../utils/ui.js';
+import { storage, KEYS } from '../utils/storage.js';
 
 export class MenuScene extends Scene {
   constructor() {
@@ -111,7 +112,7 @@ export class MenuScene extends Scene {
       { rank: 1, addr: '0xMonad...Dev', score: 99999 },
       { rank: 2, addr: '0xAlice...xyz', score: 87500 },
       { rank: 3, addr: '0xBob...abc', score: 74200 },
-      { rank: 4, addr: '0xYou', score: parseInt(localStorage.getItem('naddie_best_score') || '0', 10) },
+      { rank: 4, addr: '0xYou', score: storage.getInt(KEYS.best, 0) },
     ];
     mock.forEach((entry, i) => {
       const y = height * 0.32 + i * 55;
@@ -132,7 +133,7 @@ export class MenuScene extends Scene {
   showAchievements() {
     const { width, height } = this.scale;
     const all = AchievementsManager.getAll();
-    const unlocked = JSON.parse(localStorage.getItem('naddie_achievements_v1') || '{}');
+    const unlocked = storage.getJSON(KEYS.achievements, {}) || {};
 
     const elements = [];
     const overlay = this.add.rectangle(width / 2, height / 2, width, height, 0x000000, 0.75).setDepth(100);