refactor: replace direct WeChat/Alipay with unified pay-api gateway

Switch from direct WeChat Pay / Alipay integrations to the unified
宇之然 pay-api gateway (HMAC-SHA256 auth). Removes wechat_pay.py,
keeps PaymentGateway abstraction, adds UnifiedPayService. Simplifies
payment.py create_order to {plan, pay_type} params. Single webhook
endpoint replaces separate WeChat/Alipay notify handlers.

uni-app/src/pages/index/index.vue

@@ -277,28 +277,64 @@
     </view>
 
     <view class="footer">
+      <view class="footer-qrcode">
+        <view class="qrcode-item">
+          <image src="/static/images/yzr/yuzhiran.jpg" class="qrcode-img" mode="aspectFill" />
+          <text class="qrcode-label">公众号</text>
+        </view>
+        <view class="qrcode-item">
+          <image src="/static/images/yzr/yuzhiran-tech.jpg" class="qrcode-img" mode="aspectFill" />
+          <text class="qrcode-label">服务号</text>
+        </view>
+        <view class="qrcode-item">
+          <image src="/static/images/yzr/yuzhiran-yhl.jpg" class="qrcode-img" mode="aspectFill" />
+          <text class="qrcode-label">小程序</text>
+        </view>
+        <view class="qrcode-item">
+          <image src="/static/images/yzr/kefu.png" class="qrcode-img" mode="aspectFill" />
+          <text class="qrcode-label">客服</text>
+        </view>
+      </view>
       <view class="footer-links">
         <text class="footer-link" @click="goToPage(PAGES.AGREEMENT_PRIVACY)">隐私政策</text>
         <text class="footer-divider">|</text>
         <text class="footer-link" @click="goToPage(PAGES.AGREEMENT_TERMS)">用户协议</text>
       </view>
       <view class="footer-beian">
-        <a class="footer-beian-link" :href="EXTERNAL_URLS.BEIAN" target="_blank">{{ APP_INFO.ICP }}</a>
-        <a class="footer-beian-link" :href="EXTERNAL_URLS.BEIAN_PSB" target="_blank">{{ APP_INFO.PSB }}</a>
+        <a class="footer-beian-link" :href="beianUrl" target="_blank">{{ beianIcp }}</a>
+        <text class="footer-divider">|</text>
+        <a class="footer-beian-link" :href="beianPsbUrl" target="_blank">{{ beianPsb }}</a>
       </view>
-      <text class="footer-copyright">© {{ APP_INFO.COPYRIGHT }}. 保留所有权利.</text>
+      <text class="footer-copyright">© {{ copyrightYear }} 北京宇之然科技中心. 保留所有权利.</text>
     </view>
     <AiAssistant />
   </view>
 </template>
 
 <script setup>
-import { ref, onUnmounted } from 'vue'
+import { ref, computed, onUnmounted } from 'vue'
 import { onShow } from '@dcloudio/uni-app'
 import { authApi, customerApi, analyticsApi, onboardingApi, notificationApi, followupApi, translateApi, BASE_URL } from '@/utils/api.js'
 import AiAssistant from '@/components/ai-assistant.vue'
 import { STORAGE_KEYS, PAGES, EXTERNAL_URLS, APP_INFO, EXTRACT_FIELD_LABELS } from '@/config.js'
 
+const beianInfo = computed(() => {
+  let hostname = ''
+  try { hostname = window.location.hostname } catch {}
+  if (hostname === 'yuzhiran.com' || hostname === 'www.yuzhiran.com') {
+    return { icp: '京ICP备2026007249号-1', psb: '京公网安备11011502039545号', psbUrl: 'https://beian.mps.gov.cn/#/query/webSearch?code=11011502039545' }
+  }
+  if (hostname === 'yuzhiran.com.cn' || hostname === 'www.yuzhiran.com.cn') {
+    return { icp: '京ICP备2026007249号-2', psb: '京公网安备11011502039622号', psbUrl: 'https://beian.mps.gov.cn/#/query/webSearch?code=11011502039622' }
+  }
+  return { icp: APP_INFO.ICP, psb: APP_INFO.PSB, psbUrl: EXTERNAL_URLS.BEIAN_PSB }
+})
+const beianUrl = computed(() => EXTERNAL_URLS.BEIAN)
+const beianIcp = computed(() => beianInfo.value.icp)
+const beianPsb = computed(() => beianInfo.value.psb)
+const beianPsbUrl = computed(() => beianInfo.value.psbUrl)
+const copyrightYear = computed(() => new Date().getFullYear())
+
 const showAnnouncement = ref(false)
 const currentAnnouncement = ref(0)
 const announcements = [
@@ -1239,10 +1275,53 @@ const playTryResult = () => {
 }
 
 .footer {
-  margin-top: 40rpx;
-  padding: 40rpx 20rpx 30rpx;
+  padding: 30rpx 20rpx 20rpx;
+  background: #f8f8f8;
   text-align: center;
-  border-top: 2rpx solid #e8e8e8;
+}
+
+.footer-qrcode {
+  display: flex;
+  justify-content: center;
+  gap: 24rpx;
+  margin-bottom: 20rpx;
+  flex-wrap: wrap;
+}
+
+.qrcode-item {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 6rpx;
+}
+
+.qrcode-img {
+  width: 80rpx;
+  height: 80rpx;
+  border-radius: 10rpx;
+}
+
+.qrcode-label {
+  font-size: 20rpx;
+  color: #999;
+}
+
+.footer-links {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  gap: 16rpx;
+  margin-bottom: 12rpx;
+}
+
+.footer-link {
+  font-size: 24rpx;
+  color: #666;
+}
+
+.footer-divider {
+  font-size: 24rpx;
+  color: #d9d9d9;
 }
 
 .footer-links {