fix: correct chat endpoint URL in AiModelControllerTest

The runtime SSRF test called /api/ai/chat, but the actual endpoint is
/api/ai/model/chat (mapped via @RequestMapping("/api/ai/model") +
@PostMapping("/chat")).

application/src/test/java/org/thingsboard/server/controller/AiModelControllerTest.java

@@ -195,7 +195,7 @@ public class AiModelControllerTest extends AbstractControllerTest {
                     modelConfig);
 
             // WHEN
-            TbChatResponse response = doPost("/api/ai/chat", chatRequest, TbChatResponse.class);
+            TbChatResponse response = doPost("/api/ai/model/chat", chatRequest, TbChatResponse.class);
 
             // THEN
             assertThat(response).isInstanceOf(TbChatResponse.Failure.class);