feat: 新增AI创作中心场景，支持改写/续写/创作

client/js/scenes/HomeScene.js

@@ -116,6 +116,24 @@ export default class HomeScene extends BaseScene {
     ctx.fillStyle = 'rgba(255,255,255,0.6)';
     ctx.font = '13px sans-serif';
     ctx.fillText('每个选择，都是一个新世界', 20, 75);
+
+    // AI创作入口按钮
+    const btnWidth = 80;
+    const btnHeight = 32;
+    const btnX = this.screenWidth - btnWidth - 15;
+    const btnY = 35;
+    const btnGradient = ctx.createLinearGradient(btnX, btnY, btnX + btnWidth, btnY);
+    btnGradient.addColorStop(0, '#a855f7');
+    btnGradient.addColorStop(1, '#ec4899');
+    ctx.fillStyle = btnGradient;
+    this.roundRect(ctx, btnX, btnY, btnWidth, btnHeight, 16);
+    ctx.fill();
+    ctx.fillStyle = '#ffffff';
+    ctx.font = 'bold 12px sans-serif';
+    ctx.textAlign = 'center';
+    ctx.fillText('✨ AI创作', btnX + btnWidth / 2, btnY + 21);
+    
+    this.aiCreateBtnRect = { x: btnX, y: btnY, width: btnWidth, height: btnHeight };
   }
 
   renderCategories(ctx) {
@@ -470,6 +488,15 @@ export default class HomeScene extends BaseScene {
     const x = touch.clientX;
     const y = touch.clientY;
 
+    // 检测AI创作按钮点击
+    if (this.aiCreateBtnRect) {
+      const btn = this.aiCreateBtnRect;
+      if (x >= btn.x && x <= btn.x + btn.width && y >= btn.y && y <= btn.y + btn.height) {
+        this.main.sceneManager.switchScene('aiCreate');
+        return;
+      }
+    }
+
     // 检测Tab栏点击
     if (y > this.screenHeight - 65) {
       const tabWidth = this.screenWidth / 3;