feat(flows): 新增流程编辑器基础功能与相关组件

feat(backend): 添加流程模型与服务支持
feat(frontend): 实现流程编辑器UI与交互
feat(assets): 添加流程节点图标资源
feat(plugins): 实现上下文菜单和运行时插件
feat(components): 新增基础节点和侧边栏组件
feat(routes): 添加流程相关路由配置
feat(models): 创建流程和运行日志数据模型
feat(services): 实现流程服务层逻辑
feat(migration): 添加流程相关数据库迁移
feat(config): 更新前端配置支持流程编辑器
feat(utils): 增强axios错误处理和工具函数

backend/linear-async-create.json

@@ -0,0 +1,15 @@
+{
+  "name": "linear-async",
+  "code": "linear_async_1",
+  "design_json": {
+    "name": "linear-async",
+    "executionMode": "async",
+    "nodes": [
+      { "id": "N1", "type": "http", "data": { "title": "A-GET", "api": { "method": "GET", "url": "https://httpbin.org/delay/1" } } },
+      { "id": "N2", "type": "http", "data": { "title": "B-UUID", "api": { "method": "GET", "url": "https://httpbin.org/uuid" } } }
+    ],
+    "edges": [
+      { "sourceNodeID": "N1", "targetNodeID": "N2" }
+    ]
+  }
+}