feat: add http rate limiting

backend/config.full.toml

@@ -38,6 +38,13 @@ Port = 8080 # HTTP 监听端口
 # AllowMethods = "GET,POST,PUT,DELETE"
 # ExposeHeaders = "X-Request-Id"
 # AllowCredentials = true
+
+[Http.RateLimit]
+# Enabled = true
+# Max = 120                  # 每窗口最大请求数
+# WindowSeconds = 60         # 窗口大小（秒）
+# Message = "Too Many Requests"
+# SkipPaths = ["/healthz", "/readyz"]
 # =========================
 # Connection Multiplexer (providers/cmux)
 # 用于同端口同时暴露 HTTP + gRPC：cmux -> 分发到 Http/Grpc