Decouple UI controls from ocean camera movement

- Set scrollFactor(0) on all UI elements to fix them to screen
- HUD, crosshair, harpoons, buttons, and messages now ignore camera sway
- Only whale and ocean background move with camera
- Updated collision detection to convert whale world position to screen space
- Harpoons shoot straight relative to screen, not world
- Creates stable aiming interface while ocean/whale sway dynamically
- Much better gameplay feel with separated control and world layers

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

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

src/scenes/HuntingScene.js

@@ -153,6 +153,7 @@ export default class HuntingScene extends Phaser.Scene {
 
         this.crosshair = this.add.sprite(400, 300, 'crosshair');
         this.crosshair.setDepth(100);
+        this.crosshair.setScrollFactor(0); // Fixed to screen, ignores camera movement
     }
 
     createOceanWaves() {
@@ -175,31 +176,36 @@ export default class HuntingScene extends Phaser.Scene {
     }
 
     createHUD() {
-        // HUD background
+        // HUD background (fixed to screen, ignores camera movement)
         const hudBg = this.add.rectangle(400, 30, 780, 50, 0x000000, 0.7);
         hudBg.setStrokeStyle(2, 0xffffff);
+        hudBg.setScrollFactor(0);
 
-        // Stats
+        // Stats (fixed to screen)
         this.statsText = this.add.text(20, 15, '', {
             fontSize: '16px',
             fill: '#fff'
         });
+        this.statsText.setScrollFactor(0);
 
-        // Control mode indicator
+        // Control mode indicator (fixed to screen)
         this.controlModeText = this.add.text(400, 15, 'Controls: MOUSE (TAB to switch)', {
             fontSize: '16px',
             fill: '#ffff00'
         }).setOrigin(0.5, 0);
+        this.controlModeText.setScrollFactor(0);
 
-        // Return button
+        // Return button (fixed to screen)
         const returnBtn = this.add.rectangle(750, 30, 80, 35, 0x8B0000);
         returnBtn.setInteractive({ useHandCursor: true });
         returnBtn.setStrokeStyle(2, 0xffffff);
+        returnBtn.setScrollFactor(0);
 
-        this.add.text(750, 30, 'RETURN', {
+        const returnText = this.add.text(750, 30, 'RETURN', {
             fontSize: '14px',
             fill: '#fff'
         }).setOrigin(0.5);
+        returnText.setScrollFactor(0);
 
         returnBtn.on('pointerdown', () => {
             this.returnToMap();
@@ -223,6 +229,7 @@ export default class HuntingScene extends Phaser.Scene {
             backgroundColor: '#000000',
             padding: { x: 10, y: 5 }
         }).setOrigin(0.5);
+        this.messageText.setScrollFactor(0); // Fixed to screen
     }
 
     showMessage(text) {
@@ -312,15 +319,17 @@ export default class HuntingScene extends Phaser.Scene {
     }
 
     shootHarpoon() {
-        // Create harpoon at crosshair position
+        // Create harpoon at crosshair position (fixed to screen)
         const harpoon = this.add.rectangle(this.crosshairX, this.crosshairY, 4, 20, 0x8B4513);
         harpoon.setData('speed', 8);
         harpoon.setData('active', true);
+        harpoon.setScrollFactor(0); // Fixed to screen
 
         this.harpoons.push(harpoon);
 
-        // Sound effect simulation (flash)
+        // Sound effect simulation (flash) - fixed to screen
         const flash = this.add.circle(this.crosshairX, this.crosshairY, 10, 0xffff00, 0.8);
+        flash.setScrollFactor(0);
         this.tweens.add({
             targets: flash,
             alpha: 0,
@@ -363,10 +372,15 @@ export default class HuntingScene extends Phaser.Scene {
                 continue;
             }
 
-            // Simple collision detection
+            // Collision detection accounting for camera offset
+            // Harpoon is in screen space (scrollFactor 0)
+            // Whale is in world space, so convert to screen space
+            const whaleScreenX = whale.x - this.cameras.main.scrollX;
+            const whaleScreenY = whale.y - this.cameras.main.scrollY;
+
             const distance = Phaser.Math.Distance.Between(
                 harpoon.x, harpoon.y,
-                whale.x, whale.y
+                whaleScreenX, whaleScreenY
             );
 
             if (distance < 40) {
@@ -482,8 +496,9 @@ export default class HuntingScene extends Phaser.Scene {
         // Show success message
         this.showMessage(`Whale killed! +1 Whale Oil, -2 Fuel (Oil: ${this.inventory.whaleOil}, Fuel: ${this.inventory.fuel})`);
 
-        // Success flash
+        // Success flash (fixed to screen)
         const flash = this.add.rectangle(400, 300, 800, 600, 0xffffff, 0.3);
+        flash.setScrollFactor(0);
         this.tweens.add({
             targets: flash,
             alpha: 0,