feat: 将工作流分享改为独立页面

- 新增无后台布局的工作流分享与失效路由

- 同步分享地址并保留旧链接兼容

- 补充前后端分享链路测试

easyflow-api/easyflow-api-admin/src/test/java/tech/easyflow/admin/controller/ai/WorkflowShareControllerTest.java

@@ -28,7 +28,7 @@ public class WorkflowShareControllerTest {
 
         Assert.assertEquals(
                 buildShareBaseUrl(request),
-                "https://example.test/easyflow/ai/workflow/design"
+                "https://example.test/easyflow/share/workflow"
         );
     }
 
@@ -47,7 +47,7 @@ public class WorkflowShareControllerTest {
 
         Assert.assertEquals(
                 buildShareBaseUrl(request),
-                "https://example.test/easyflow/ai/workflow/design"
+                "https://example.test/easyflow/share/workflow"
         );
     }