feat: AI routing DB-driven, payment gateway full integration, WeChat mini-program CI/CD

- AI routing rules now stored in system_configs DB table instead of hardcoded config
- Multi-model support via name|model composite key for same-provider routing
- UnifiedPayService with HMAC-SHA256 gateway integration (alipay/wechat)
- Admin payment panel: list, stats, search, filter, refund
- WeChat mini-program CI/CD via miniprogram-ci (v1.0.9)
- Translation quota extended to LLM provider tier
- SearchService with DB-driven provider config (bing/google_cse/searxng)
- Footer cleanup across admin/workspace/uni-app
- Private key excluded from git tracking

backend/app/services/payment_gateway.py

@@ -30,6 +30,9 @@ class PaymentGateway(ABC):
     def parse_callback(self, body: str, headers: dict) -> Dict[str, Any]:
         ...
 
+    async def close_order(self, order_no: str) -> Dict[str, Any]:
+        raise NotImplementedError
+
     def supports(self, pay_type: str) -> bool:
         return pay_type in self.supported_types