Add whale swimming and diving mechanics

- Whales now swim across screen with directional movement
- Random horizontal speed (0.5-1.0) and vertical drift
- Bounces off screen edges and flips direction
- Diving behavior: dives every 3-7 seconds for 2 seconds
- Fades to 20% opacity when diving, full when surfaced
- Cannot be hit while diving (invulnerable)
- Shows dive/surface messages
- Combines swimming with bobbing animation
- Much more dynamic and challenging hunting
- Whales are now moving targets instead of stationary

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

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

src/scenes/HuntingScene.js

@@ -281,10 +281,17 @@ export default class HuntingScene extends Phaser.Scene {
         whale.setData('bodyWidth', 80);
         whale.setData('bodyHeight', 40);
         whale.setData('healthBar', healthBar);
-        whale.setData('baseX', x); // Store original position for bobbing
-        whale.setData('baseY', y);
         whale.setData('bobTime', 0); // Timer for bobbing animation
 
+        // Swimming movement
+        whale.setData('swimSpeedX', direction * (0.5 + Math.random() * 0.5)); // 0.5-1.0 speed
+        whale.setData('swimSpeedY', (Math.random() - 0.5) * 0.3); // Slight vertical drift
+
+        // Diving mechanics
+        whale.setData('diving', false);
+        whale.setData('diveTimer', 0);
+        whale.setData('nextDiveTime', 3 + Math.random() * 4); // Dive every 3-7 seconds
+
         // Flip if moving right
         if (direction > 0) {
             whale.setScale(-1, 1);
@@ -304,20 +311,66 @@ export default class HuntingScene extends Phaser.Scene {
             return;
         }
 
-        // Gentle bobbing movement
+        // Update dive timer
+        let diveTimer = whale.getData('diveTimer');
+        diveTimer += 0.016; // ~60fps
+        whale.setData('diveTimer', diveTimer);
+
+        // Handle diving behavior
+        const diving = whale.getData('diving');
+        const nextDiveTime = whale.getData('nextDiveTime');
+
+        if (!diving && diveTimer >= nextDiveTime) {
+            // Start diving
+            this.startDive(whale);
+        } else if (diving && diveTimer >= nextDiveTime + 2) {
+            // Resurface after 2 seconds
+            this.endDive(whale);
+        }
+
+        // Swimming movement
+        const swimSpeedX = whale.getData('swimSpeedX');
+        const swimSpeedY = whale.getData('swimSpeedY');
+        whale.x += swimSpeedX;
+        whale.y += swimSpeedY;
+
+        // Bobbing animation (on top of swimming)
         let bobTime = whale.getData('bobTime');
         bobTime += 0.02;
         whale.setData('bobTime', bobTime);
 
-        const baseX = whale.getData('baseX');
-        const baseY = whale.getData('baseY');
+        const bobOffsetX = Math.sin(bobTime) * 15; // Reduced from 30 since we're swimming
+        const bobOffsetY = Math.cos(bobTime * 0.7) * 10; // Reduced from 20
 
-        // Horizontal and vertical oscillation
-        const offsetX = Math.sin(bobTime) * 30; // 30 pixels horizontal movement
-        const offsetY = Math.cos(bobTime * 0.7) * 20; // 20 pixels vertical movement
+        whale.x += bobOffsetX;
+        whale.y += bobOffsetY;
 
-        whale.x = baseX + offsetX;
-        whale.y = baseY + offsetY;
+        // Bounce off screen edges
+        if (whale.x < 50 || whale.x > 750) {
+            whale.setData('swimSpeedX', -swimSpeedX);
+            whale.setScale(whale.scaleX * -1, whale.scaleY); // Flip whale
+        }
+        if (whale.y < 100 || whale.y > 550) {
+            whale.setData('swimSpeedY', -swimSpeedY);
+        }
+
+        // Update opacity based on diving
+        if (diving) {
+            whale.alpha = Math.max(0.2, whale.alpha - 0.05);
+        }
+    }
+
+    startDive(whale) {
+        whale.setData('diving', true);
+        this.showMessage('Whale is diving!');
+    }
+
+    endDive(whale) {
+        whale.setData('diving', false);
+        whale.setData('diveTimer', 0);
+        whale.setData('nextDiveTime', 3 + Math.random() * 4); // Next dive in 3-7 seconds
+        whale.alpha = 1; // Full opacity
+        this.showMessage('Whale surfaced!');
     }
 
     shootHarpoon() {
@@ -367,6 +420,11 @@ export default class HuntingScene extends Phaser.Scene {
 
         const whale = this.currentWhale;
 
+        // Can't hit whale while diving
+        if (whale.getData('diving')) {
+            return;
+        }
+
         for (let h = this.harpoons.length - 1; h >= 0; h--) {
             const harpoon = this.harpoons[h];