refactor(wish-tree): 用 WebGL 重写许愿树

- 移除 Canvas 2D 绘制，改用 WebGL
- 手写着色器实现光照和发光效果
- 树干使用圆柱体变形，带扭曲效果
- 树冠使用多层变形球体，带噪声
- 相机自动旋转，可触摸控制
- 保留陀螺仪和麦克风交互
- 简化场景，只保留一棵祈福树
- 深色主题 UI，金色点缀

mini/pages/wish-tree/wish-tree.wxml

@@ -1,22 +1,19 @@
 <view class="container">
-  <!-- 全屏画布 -->
+  <!-- WebGL Canvas -->
   <canvas 
-    canvas-id="wishTree" 
-    class="wish-tree-canvas"
-    style="width: {{canvasWidth}}px; height: {{canvasHeight}}px;"
+    type="webgl"
+    id="webgl-canvas"
+    class="webgl-canvas"
     bindtouchstart="onCanvasTouch"
+    bindtouchmove="onCanvasMove"
+    bindtouchend="onCanvasEnd"
   ></canvas>
 
   <!-- 顶部导航 -->
   <view class="top-bar">
-    <view class="tree-switcher">
-      <view class="switch-btn" bindtap="switchTree" data-direction="prev">
-        <text class="switch-icon">‹</text>
-      </view>
-      <view class="tree-name">{{trees.length > 0 ? trees[currentTreeIndex].name : '许愿树'}}</view>
-      <view class="switch-btn" bindtap="switchTree" data-direction="next">
-        <text class="switch-icon">›</text>
-      </view>
+    <view class="tree-info">
+      <text class="tree-name">{{treeName}}</text>
+      <text class="tree-desc">{{treeDesc}}</text>
     </view>
     
     <!-- 传感器控制 -->