feat: 小程序演示版改造 + 服务端安全加固

- 许愿树移除付费许愿/商品选择/微信支付调用，全部走免费许愿
- 许愿发布前接入微信 msgSecCheck v2 内容安全检测（access_token 内存缓存）
- 许愿字数限制改为按字符计算（中文按 1 字计）
- 占卜页改名「民俗趣算」并弱化「算命」措辞，占卜/每日运势页加文化声明
- 生产环境 JWT_SECRET 缺失或为默认值/不足 32 位时拒绝启动

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

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

@@ -122,64 +122,22 @@
       </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}}"
+          maxlength="{{maxFreeLength}}"
           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="product-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>
+          {{wishContent.length}}/{{maxFreeLength}}
         </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>
+        <button class="btn-primary" bindtap="submitWish">提交许愿</button>
       </view>
     </view>
   </view>