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.

admin-frontend/src/layouts/AdminLayout.vue

@@ -92,14 +92,47 @@
       </el-main>
 
       <el-footer class="footer">
-        <span>TradeMate 外贸小助手 &copy; {{ new Date().getFullYear() }}</span>
+        <div class="footer-content">
+          <div class="footer-section">
+            <div class="footer-brand">TradeMate</div>
+            <p class="footer-tagline">AI 外贸小助手 · 让外贸更简单</p>
+            <div class="qrcode-row">
+              <div class="qrcode-item">
+                <img src="/images/yzr/yuzhiran.jpg" alt="微信公众号" class="qrcode-img" />
+                <span>微信公众号</span>
+              </div>
+              <div class="qrcode-item">
+                <img src="/images/yzr/yuzhiran-tech.jpg" alt="微信服务号" class="qrcode-img" />
+                <span>微信服务号</span>
+              </div>
+              <div class="qrcode-item">
+                <img src="/images/yzr/yuzhiran-yhl.jpg" alt="小程序" class="qrcode-img" />
+                <span>小程序</span>
+              </div>
+              <div class="qrcode-item">
+                <img src="/images/yzr/kefu.png" alt="客服" class="qrcode-img" />
+                <span>微信客服</span>
+              </div>
+            </div>
+          </div>
+          <div class="footer-bottom">
+            <p>&copy; {{ new Date().getFullYear() }} TradeMate 外贸小助手. 保留所有权利.</p>
+            <div class="footer-links">
+              <a href="http://beian.miit.gov.cn/" target="_blank">{{ beianInfo.icp }}</a>
+              <a v-if="beianInfo.showGongan" :href="beianInfo.gonganLink" target="_blank" rel="noreferrer" class="gongan-link">
+                <img src="/images/beian/gongan-beian.png" alt="公安备案" class="gongan-icon" />
+                {{ beianInfo.gongan }}
+              </a>
+            </div>
+          </div>
+        </div>
       </el-footer>
     </el-container>
   </el-container>
 </template>
 
 <script setup>
-import { ref } from 'vue'
+import { ref, computed } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useAuthStore } from '@/stores/auth'
 
@@ -107,6 +140,17 @@ const route = useRoute()
 const router = useRouter()
 const auth = useAuthStore()
 const collapsed = ref(false)
+
+const beianInfo = computed(() => {
+  const hostname = window.location.hostname
+  if (hostname === 'yuzhiran.com' || hostname === 'www.yuzhiran.com') {
+    return { icp: '京ICP备2026007249号-1', gongan: '京公网安备11011502039545号', gonganLink: 'https://beian.mps.gov.cn/#/query/webSearch?code=11011502039545', showGongan: true }
+  }
+  if (hostname === 'yuzhiran.com.cn' || hostname === 'www.yuzhiran.com.cn') {
+    return { icp: '京ICP备2026007249号-2', gongan: '京公网安备11011502039622号', gonganLink: 'https://beian.mps.gov.cn/#/query/webSearch?code=11011502039622', showGongan: true }
+  }
+  return { icp: '京ICP备2026007249号-1', gongan: '京公网安备11011502039545号', gonganLink: 'https://beian.mps.gov.cn/#/query/webSearch?code=11011502039545', showGongan: true }
+})
 </script>
 
 <style scoped>
@@ -125,5 +169,18 @@ const collapsed = ref(false)
 .user-info { display: flex; align-items: center; gap: 8px; cursor: pointer; }
 .user-name { font-size: 14px; color: #333; }
 .main-content { background: #f5f5f5; padding: 20px; overflow-y: auto; }
-.footer { display: flex; align-items: center; justify-content: center; height: 48px; background: #fff; border-top: 1px solid #e8e8e8; color: #999; font-size: 12px; }
+.footer { padding: 0; background: #fff; border-top: 1px solid #e8e8e8; color: #666; font-size: 12px; }
+.footer-content { padding: 20px 24px 16px; }
+.footer-section { margin-bottom: 16px; }
+.footer-brand { font-size: 15px; font-weight: 700; color: #1890ff; margin-bottom: 4px; }
+.footer-tagline { color: #999; font-size: 12px; margin-bottom: 12px; }
+.qrcode-row { display: flex; gap: 16px; flex-wrap: wrap; }
+.qrcode-item { display: flex; flex-direction: column; align-items: center; gap: 4px; color: #999; font-size: 11px; }
+.qrcode-img { width: 48px; height: 48px; border-radius: 6px; }
+.footer-bottom { border-top: 1px solid #eee; padding-top: 12px; display: flex; justify-content: center; align-items: center; gap: 16px; flex-wrap: wrap; }
+.footer-links { display: flex; gap: 16px; align-items: center; }
+.footer-links a { color: #999; text-decoration: none; }
+.footer-links a:hover { color: #1890ff; }
+.gongan-link { display: inline-flex; align-items: center; gap: 4px; }
+.gongan-icon { height: 16px; vertical-align: middle; }
 </style>