feat: 添加许愿树功能和Go后端服务

- 新增许愿树页面（Canvas绘制、许愿条展示）
- 新增许愿详情页面
- 新增许愿创建弹窗（免费/付费两种模式）
- 新增网络请求封装 utils/request.js
- 新增Go后端项目结构（Gin + Inertia.js）
- 新增用户、订单、许愿数据模型
- 新增数据库迁移脚本
- 更新.gitignore补全忽略规则
- 更新.env.local配置（robot=2, 版本1.0.1）
- 添加secrets目录说明文档

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

@@ -0,0 +1,117 @@
+<view class="container">
+  <!-- 许愿树画布 -->
+  <view class="canvas-container">
+    <canvas 
+      canvas-id="wishTree" 
+      class="wish-tree-canvas"
+      style="width: {{canvasWidth}}px; height: {{canvasHeight}}px;"
+    ></canvas>
+    
+    <!-- 许愿条覆盖层 -->
+    <view class="wishes-overlay">
+      <view 
+        wx:for="{{wishes}}" 
+        wx:key="id"
+        class="wish-tag {{item.type}} {{item.isRobot ? 'robot' : ''}}"
+        style="left: {{item.x}}px; top: {{item.y}}px;"
+        bindtap="viewWishDetail"
+        data-id="{{item.id}}"
+      >
+        <text class="wish-text">{{item.content}}</text>
+        <view class="wish-badge" wx:if="{{item.type === 'paid'}}">VIP</view>
+      </view>
+    </view>
+  </view>
+
+  <!-- 许愿按钮 -->
+  <view class="action-bar">
+    <button class="btn-primary btn-wish" bindtap="openCreateModal">
+      <text class="icon">🙏</text>
+      <text>我要许愿</text>
+    </button>
+  </view>
+
+  <!-- 许愿说明 -->
+  <view class="tips-section">
+    <view class="tip-item">
+      <text class="tip-icon">🎋</text>
+      <text class="tip-text">免费许愿：20字以内，可能被覆盖</text>
+    </view>
+    <view class="tip-item">
+      <text class="tip-icon">✨</text>
+      <text class="tip-text">付费许愿：100字以内，优先展示，长期保留</text>
+    </view>
+  </view>
+
+  <!-- 许愿弹窗 -->
+  <view class="modal" wx:if="{{showCreateModal}}">
+    <view class="modal-mask" bindtap="closeCreateModal"></view>
+    <view class="modal-content">
+      <view class="modal-header">
+        <text class="modal-title">许下心愿</text>
+        <text class="modal-close" bindtap="closeCreateModal">×</text>
+      </view>
+      
+      <view class="modal-body">
+        <!-- 许愿类型选择 -->
+        <view class="type-selector">
+          <view 
+            class="type-item {{wishType === 'free' ? 'active' : ''}}"
+            bindtap="selectType"
+            data-type="free"
+          >
+            <text class="type-name">免费许愿</text>
+            <text class="type-desc">20字以内</text>
+          </view>
+          <view 
+            class="type-item {{wishType === 'paid' ? 'active' : ''}}"
+            bindtap="selectType"
+            data-type="paid"
+          >
+            <text class="type-name">付费许愿</text>
+            <text class="type-desc">更多特权</text>
+          </view>
+        </view>
+
+        <!-- 许愿内容输入 -->
+        <textarea 
+          class="wish-input"
+          placeholder="请输入你的愿望..."
+          maxlength="{{wishType === 'free' ? maxFreeLength : maxPaidLength}}"
+          bindinput="onInputContent"
+          value="{{wishContent}}"
+        ></textarea>
+        <view class="input-count">
+          {{wishContent.length}}/{{wishType === 'free' ? maxFreeLength : maxPaidLength}}
+        </view>
+
+        <!-- 付费商品选择 -->
+        <view class="product-section" wx:if="{{wishType === 'paid'}}">
+          <view class="section-title">选择许愿商品</view>
+          <view class="product-list">
+            <view 
+              wx:for="{{products}}" 
+              wx:key="id"
+              class="product-item {{selectedProduct && selectedProduct.id === item.id ? 'active' : ''}}"
+              bindtap="selectProduct"
+              data-id="{{item.id}}"
+            >
+              <view class="product-info">
+                <text class="product-name">{{item.name}}</text>
+                <text class="product-desc">展示{{item.duration}}天</text>
+              </view>
+              <view class="product-price">¥{{item.price / 100}}</view>
+            </view>
+          </view>
+        </view>
+      </view>
+      
+      <view class="modal-footer">
+        <button class="btn-outline" bindtap="closeCreateModal">取消</button>
+        <button class="btn-primary" bindtap="submitWish">
+          {{wishType === 'paid' ? '支付并许愿' : '提交许愿'}}
+        </button>
+      </view>
+    </view>
+  </view>
+</view>