Update fuel barrel message to reference boiling whale blubber

Changed message to clarify fuel is for cooking whale oil,
not for running the ship.

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/scenes/ShipDeckScene.js

@@ -59,7 +59,7 @@ export default class ShipDeckScene extends Phaser.Scene {
         }).setOrigin(0.5);
 
         fuelBarrel.on('pointerdown', () => {
-            this.showMessage(`Fuel barrel: ${this.inventory.fuel} units remaining. This keeps the ship running.`);
+            this.showMessage(`Fuel barrel: ${this.inventory.fuel} units remaining. Needed for boiling down whale blubber.`);
         });
 
         // Whale oil barrel