feat: 增强智能体模型调用兼容能力

- 增加模型流式开关和 HTTP 传输策略配置

- 使用 AgentScope 执行基础连接、流式与 VLM 双阶段验证

- 固定多模态校验图片并统一验证状态展示

easyflow-modules/easyflow-module-ai/src/test/java/tech/easyflow/ai/service/support/VlmVerificationImageTest.java

@@ -0,0 +1,32 @@
+package tech.easyflow.ai.service.support;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayInputStream;
+
+/**
+ * VLM 连接验证专用 PNG 测试。
+ */
+public class VlmVerificationImageTest {
+
+    /**
+     * 验证固定资源图片可重复读取并能被标准 PNG 解码器解析。
+     *
+     * @throws Exception 图片解码失败时抛出
+     */
+    @Test
+    public void pngBytesShouldReturnDeterministicReadableImage() throws Exception {
+        byte[] first = VlmVerificationImage.pngBytes();
+        byte[] second = VlmVerificationImage.pngBytes();
+        BufferedImage image = ImageIO.read(new ByteArrayInputStream(first));
+
+        Assert.assertArrayEquals(first, second);
+        Assert.assertNotNull(image);
+        Assert.assertEquals(480, image.getWidth());
+        Assert.assertEquals(180, image.getHeight());
+        Assert.assertEquals("5839", VlmVerificationImage.VERIFICATION_CODE);
+    }
+}