Phase 2: ECS foundation — world, components, systems, bridge

- bitECS world with time tracking (delta, elapsed, tick)
- 5 components: Position, Velocity, SpriteRef, Health, ChemicalComposition
- Movement system (velocity * delta) + bounce system (boundary reflection)
- Health system with damage, healing, death detection
- Entity factory (createGameEntity/removeGameEntity)
- Phaser bridge: polling sync creates/destroys/updates circle sprites
- GameScene: 20 colored circles bouncing at 60fps
- BootScene: click-to-start transition, version bump to v0.2.0
- 39 ECS unit tests passing (74 total)

Co-authored-by: Cursor <cursoragent@cursor.com>

src/scenes/GameScene.ts

@@ -0,0 +1,91 @@
+import Phaser from 'phaser';
+import { createGameWorld, updateTime, type GameWorld } from '../ecs/world';
+import { movementSystem, bounceSystem } from '../ecs/systems/movement';
+import { healthSystem } from '../ecs/systems/health';
+import { createGameEntity, removeGameEntity } from '../ecs/factory';
+import { PhaserBridge } from '../ecs/bridge';
+import { GAME_WIDTH, GAME_HEIGHT } from '../config';
+
+const ENTITY_COUNT = 20;
+const COLORS = [
+  0x00ff88, 0xff0044, 0x44aaff, 0xffaa00,
+  0xff44ff, 0x44ffaa, 0xffff44, 0xaa44ff,
+];
+
+export class GameScene extends Phaser.Scene {
+  private gameWorld!: GameWorld;
+  private bridge!: PhaserBridge;
+  private statsText!: Phaser.GameObjects.Text;
+
+  constructor() {
+    super({ key: 'GameScene' });
+  }
+
+  create(): void {
+    // 1. Initialize ECS
+    this.gameWorld = createGameWorld();
+    this.bridge = new PhaserBridge(this);
+
+    // 2. Spawn bouncing circles with random properties
+    for (let i = 0; i < ENTITY_COUNT; i++) {
+      const speed = 50 + Math.random() * 150;
+      const angle = Math.random() * Math.PI * 2;
+
+      createGameEntity(this.gameWorld.world, {
+        position: {
+          x: 100 + Math.random() * (GAME_WIDTH - 200),
+          y: 100 + Math.random() * (GAME_HEIGHT - 200),
+        },
+        velocity: {
+          vx: Math.cos(angle) * speed,
+          vy: Math.sin(angle) * speed,
+        },
+        sprite: {
+          color: COLORS[i % COLORS.length],
+          radius: 6 + Math.random() * 14,
+        },
+        health: {
+          current: 100,
+          max: 100,
+        },
+      });
+    }
+
+    // 3. UI labels
+    this.add.text(10, 10, 'Phase 2: ECS Foundation', {
+      fontSize: '14px',
+      color: '#00ff88',
+      fontFamily: 'monospace',
+    });
+
+    this.statsText = this.add.text(10, 30, '', {
+      fontSize: '12px',
+      color: '#557755',
+      fontFamily: 'monospace',
+    });
+  }
+
+  update(_time: number, delta: number): void {
+    // 1. Update world time
+    updateTime(this.gameWorld, delta);
+
+    // 2. Run systems
+    movementSystem(this.gameWorld.world, delta);
+    bounceSystem(this.gameWorld.world, GAME_WIDTH, GAME_HEIGHT);
+
+    // 3. Health check + cleanup
+    const dead = healthSystem(this.gameWorld.world);
+    for (const eid of dead) {
+      removeGameEntity(this.gameWorld.world, eid);
+    }
+
+    // 4. Sync to Phaser
+    this.bridge.sync(this.gameWorld.world);
+
+    // 5. Update stats
+    const fps = delta > 0 ? Math.round(1000 / delta) : 0;
+    this.statsText.setText(
+      `${this.bridge.entityCount} entities | tick ${this.gameWorld.time.tick} | ${fps} fps`,
+    );
+  }
+}