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-sync-create.json

@@ -0,0 +1,22 @@
+{
+  "name": "branch-sync",
+  "code": "branch_sync_1",
+  "design_json": {
+    "name": "branch-sync",
+    "executionMode": "sync",
+    "nodes": [
+      { "id": "A", "type": "http", "data": { "title": "A-GET-x", "api": { "method": "GET", "url": "https://httpbin.org/get?x=hello" } } },
+      { "id": "COND", "type": "condition", "data": { "title": "COND", "conditions": [
+        { "key": "yes", "value": { "left": { "type": "constant", "content": true }, "operator": "is_true" } },
+        { "key": "no",  "value": { "left": { "type": "constant", "content": false }, "operator": "is_true" } }
+      ] } },
+      { "id": "B", "type": "http", "data": { "title": "B-UUID", "api": { "method": "GET", "url": "https://httpbin.org/uuid" } } },
+      { "id": "C", "type": "http", "data": { "title": "C-Delay1s", "api": { "method": "GET", "url": "https://httpbin.org/delay/1" } } }
+    ],
+    "edges": [
+      { "sourceNodeID": "A", "targetNodeID": "COND" },
+      { "sourceNodeID": "COND", "targetNodeID": "B", "sourcePortID": "yes" },
+      { "sourceNodeID": "COND", "targetNodeID": "C", "sourcePortID": "no" }
+    ]
+  }
+}