fix(gateway): postToken param type BodyInserter<?, ? super ClientHttpRequest> (matches body() signature)

backend/api-gateway/src/main/java/com/deepdata/gateway/infrastructure/casdoor/CasdoorClient.java

@@ -4,6 +4,7 @@ import com.deepdata.gateway.infrastructure.casdoor.dto.CasdoorTokenResponse;
 import io.netty.channel.ChannelOption;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.http.MediaType;
+import org.springframework.http.client.reactive.ClientHttpRequest;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.stereotype.Component;
 import org.springframework.web.reactive.function.BodyInserter;
@@ -105,7 +106,7 @@ public class CasdoorClient {
      * 非 2xx 解析错误 JSON 并抛出带 error_description 的异常。
      */
     private Mono<CasdoorTokenResponse> postToken(
-            BodyInserter<?, ?> form, String op) {
+            BodyInserter<?, ? super ClientHttpRequest> form, String op) {
         return webClient.post()
                 .uri(props.getTokenUri())
                 .contentType(MediaType.APPLICATION_FORM_URLENCODED)