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/branch-async-create.json

@@ -0,0 +1,19 @@
+{
+  "name": "Branch A->COND->B/C (async)",
+  "code": "branch_async",
+  "design_json": {
+    "name": "Branch A->COND->B/C (async)",
+    "execution_mode": "async",
+    "nodes": [
+      { "id": "A", "kind": "http", "name": "http A", "task": "http", "config": { "url": "https://httpbin.org/get", "method": "GET" } },
+      { "id": "COND", "kind": "condition", "name": "cond", "task": "condition", "config": { "expression": { "left": { "type": "constant", "value": true }, "operator": "is_true", "right": { "type": "constant", "value": true } } }, "ports": { "yes": { "id": "yes" }, "no": { "id": "no" } } },
+      { "id": "B", "kind": "http", "name": "http B", "task": "http", "config": { "url": "https://httpbin.org/anything/B", "method": "GET" } },
+      { "id": "C", "kind": "http", "name": "http C", "task": "http", "config": { "url": "https://httpbin.org/anything/C", "method": "GET" } }
+    ],
+    "edges": [
+      { "from": "A", "to": "COND" },
+      { "from": "COND", "to": "B", "condition": { "left": { "type": "constant", "value": true }, "operator": "is_true", "right": { "type": "constant", "value": true } } },
+      { "from": "COND", "to": "C", "condition": { "left": { "type": "constant", "value": true }, "operator": "is_false", "right": { "type": "constant", "value": true } } }
+    ]
+  }
+}