Update debug lines to show barrel group borders

- Draw complete border around fuel barrel group
- Shows top, bottom, left, and right edges
- Helps visualize barrel group boundaries

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

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

src/scenes/ShipDeckScene.js

@@ -159,14 +159,23 @@ export default class ShipDeckScene extends Phaser.Scene {
         });
         this.fuelBarrels.push(interactiveZone);
 
-        // Debug: Draw center lines for fuel barrel group
-        const centerLines = this.add.graphics();
-        centerLines.lineStyle(2, 0xFF0000, 0.8);
-        // Horizontal center line
-        centerLines.lineBetween(zoneX - zoneWidth / 2, deckVerticalCenter, zoneX + zoneWidth / 2, deckVerticalCenter);
-        // Vertical center line
-        centerLines.lineBetween(zoneX, zoneY - zoneHeight / 2, zoneX, zoneY + zoneHeight / 2);
-        this.fuelBarrels.push(centerLines);
+        // Debug: Draw border lines for fuel barrel group
+        const borderLines = this.add.graphics();
+        borderLines.lineStyle(2, 0xFF0000, 0.8);
+
+        const left = zoneX - zoneWidth / 2;
+        const right = zoneX + zoneWidth / 2;
+        const top = zoneY - zoneHeight / 2;
+        const bottom = zoneY + zoneHeight / 2;
+
+        // Horizontal lines (top and bottom)
+        borderLines.lineBetween(left, top, right, top);
+        borderLines.lineBetween(left, bottom, right, bottom);
+        // Vertical lines (left and right)
+        borderLines.lineBetween(left, top, left, bottom);
+        borderLines.lineBetween(right, top, right, bottom);
+
+        this.fuelBarrels.push(borderLines);
     }
 
     createOilBarrels() {