perf(限流服务): 优化Redis查询以减少命令数量

使用zcount替代zremrangebyscore和zcard组合查询，减少一次Redis操作

api/app/services/api_key_service.py

@@ -292,11 +292,10 @@ class RateLimiterService:
         key = f"rate_limit:qps:{api_key_id}"
 
         async with self.redis.pipeline() as pipe:
-            pipe.zremrangebyscore(key, 0, window_start)
+            pipe.zcount(key, window_start, "+inf")
-            pipe.zcard(key)
             results = await pipe.execute()
 
-        current = results[1]
+        current = results[0]
 
         if current >= limit:
             return False, {