Add collision detection for hull damage

Implemented collision detection on the ship to automatically reduce hull integrity when colliding with objects.

**Modified: src/ship.ts**
- Added collision observable handler after physics aggregate creation
- Subscribed to getCollisionObservable() on ship physics body
- Collision handler calls shipStatus.damageHull(0.01) on any collision event
- Hull damage automatically triggers gauge update via observable pattern

This completes the full resource management system:
- **Fuel**: Consumed by linear thrust (0.005/frame) and angular thrust (0.005/frame)
- **Ammo**: Consumed by weapon firing (0.01 per shot)
- **Hull**: Damaged by collisions (0.01 per collision)
- **Gauges**: All three update automatically with color-coded feedback
- **Prevention**: Thrust disabled when fuel depleted, weapons disabled when ammo depleted

The hull gauge will now show damage in real-time as the ship collides with asteroids or other objects in the game world.

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

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

src/ship.ts

@@ -94,6 +94,15 @@ export class Ship {
                 agg.body.setAngularDamping(0.4);
                 agg.body.setAngularVelocity(new Vector3(0, 0, 0));
                 agg.body.setCollisionCallbackEnabled(true);
+
+                // Register collision handler for hull damage
+                const observable = agg.body.getCollisionObservable();
+                observable.add((collisionEvent) => {
+                    // Damage hull on any collision
+                    if (this._scoreboard?.shipStatus) {
+                        this._scoreboard.shipStatus.damageHull(0.01);
+                    }
+                });
             } else {
                 console.warn("No geometry mesh found, cannot create physics");
             }