Step 2: Track asteroids destroyed

Added real-time tracking of asteroids destroyed by listening to scoreboard score events.

**Modified: src/ship.ts**
- Subscribe to scoreboard.onScoreObservable in initialize()
- Call gameStats.recordAsteroidDestroyed() for each score event
- Each score event represents one asteroid destroyed

The Asteroids Destroyed statistic now updates in real-time on the status screen whenever an asteroid is destroyed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/ship.ts

@@ -209,6 +209,12 @@ export class Ship {
         // Initialize scoreboard (it will retrieve and setup its own screen mesh)
         this._scoreboard.initialize();
 
+        // Subscribe to score events to track asteroids destroyed
+        this._scoreboard.onScoreObservable.add((scoreEvent) => {
+            // Each score event represents an asteroid destroyed
+            this._gameStats.recordAsteroidDestroyed();
+        });
+
         // Initialize status screen
         this._statusScreen = new StatusScreen(DefaultScene.MainScene, this._gameStats);
         this._statusScreen.initialize(this._camera);