feat(ws): 新增WebSocket实时通信支持与SSE独立服务

重构中间件结构，新增ws模块实现WebSocket流程执行实时推送
将SSE服务拆分为独立端口监听，默认8866
优化前端流式模式切换，支持WS/SSE协议选择
统一流式事件处理逻辑，完善错误处理与取消机制
更新Cargo.toml依赖，添加WebSocket相关库
调整代码组织结构，规范导入分组与注释

backend/src/flow/executors/condition.rs

@@ -1,7 +1,9 @@
+// third-party
 use anyhow::Result;
 use serde_json::Value as V;
 use tracing::info;
 
+// 业务函数
 pub(crate) fn eval_condition_json(ctx: &serde_json::Value, cond: &serde_json::Value) -> Result<bool> {
     // 新增：若 cond 为数组，按 AND 语义评估（全部为 true 才为 true）
     if let Some(arr) = cond.as_array() {

backend/src/flow/executors/db.rs

@@ -1,9 +1,11 @@
+// third-party
 use async_trait::async_trait;
 use serde_json::{json, Value};
 use tracing::info;
 
-use crate::flow::task::Executor;
+// crate
 use crate::flow::domain::{NodeDef, NodeId};
+use crate::flow::task::Executor;
 
 #[derive(Default)]
 pub struct DbTask;

backend/src/flow/executors/http.rs

@@ -1,12 +1,17 @@
-use async_trait::async_trait;
-use serde_json::{Value, json, Map};
-use tracing::info;
+// std
 use std::collections::HashMap;
+
+// third-party
+use async_trait::async_trait;
+use serde_json::{json, Map, Value};
+use tracing::info;
+
+// crate
+use crate::flow::domain::{NodeDef, NodeId};
+use crate::flow::task::Executor;
 use crate::middlewares::http_client::{execute_http, HttpClientOptions, HttpRequest};
 
-use crate::flow::task::Executor;
-use crate::flow::domain::{NodeDef, NodeId};
-
+// 结构体：紧随 use
 #[derive(Default)]
 pub struct HttpTask;
 
@@ -18,6 +23,7 @@ struct HttpOpts {
     http1_only: bool,
 }
 
+// 业务实现与函数：置于最后
 #[async_trait]
 impl Executor for HttpTask {
     async fn execute(&self, node_id: &NodeId, _node: &NodeDef, ctx: &mut Value) -> anyhow::Result<()> {

backend/src/flow/executors/script_js.rs

@@ -1,12 +1,18 @@
-use async_trait::async_trait
-;
+// std
+use std::fs;
+use std::time::Instant;
+
+// third-party
+use async_trait::async_trait;
 use serde_json::Value;
 use tracing::{debug, info};
-use std::time::Instant;
-use std::fs;
 
-use crate::flow::task::Executor;
+// crate
 use crate::flow::domain::{NodeDef, NodeId};
+use crate::flow::task::Executor;
+
+#[derive(Default)]
+pub struct ScriptJsTask;
 
 fn read_node_script_file(ctx: &Value, node_id: &str, lang_key: &str) -> Option<String> {
     if let Some(nodes) = ctx.get("nodes").and_then(|v| v.as_object()) {
@@ -123,9 +129,6 @@ fn exec_js_file(node_id: &NodeId, path: &str, ctx: &mut Value) -> anyhow::Result
     exec_js_script(node_id, &code, ctx)
 }
 
-#[derive(Default)]
-pub struct ScriptJsTask;
-
 #[async_trait]
 impl Executor for ScriptJsTask {
     async fn execute(&self, node_id: &NodeId, _node: &NodeDef, ctx: &mut Value) -> anyhow::Result<()> {

backend/src/flow/executors/script_python.rs

@@ -1,10 +1,17 @@
+// std
+use std::time::Instant;
+
+// third-party
 use async_trait::async_trait;
 use serde_json::Value;
 use tracing::{debug, info};
-use std::time::Instant;
 
-use crate::flow::task::Executor;
+// crate
 use crate::flow::domain::{NodeDef, NodeId};
+use crate::flow::task::Executor;
+
+#[derive(Default)]
+pub struct ScriptPythonTask;
 
 fn read_node_script_file(ctx: &Value, node_id: &str, lang_key: &str) -> Option<String> {
     if let Some(nodes) = ctx.get("nodes").and_then(|v| v.as_object()) {
@@ -20,9 +27,6 @@ fn truncate_str(s: &str, max: usize) -> String {
     if s.len() <= max { s } else { format!("{}…", &s[..max]) }
 }
 
-#[derive(Default)]
-pub struct ScriptPythonTask;
-
 #[async_trait]
 impl Executor for ScriptPythonTask {
     async fn execute(&self, node_id: &NodeId, _node: &NodeDef, ctx: &mut Value) -> anyhow::Result<()> {

backend/src/flow/executors/script_rhai.rs

@@ -1,13 +1,19 @@
-use serde_json::Value;
-use tracing::{debug, info};
+// std
 use std::fs;
 use std::time::Instant;
 
-use crate::flow::domain::NodeId;
+// third-party
+use async_trait::async_trait;
+use serde_json::Value;
+use tracing::{debug, info};
+
+// crate
+use crate::flow::domain::{NodeDef, NodeId};
 use crate::flow::engine::eval_rhai_expr_json;
 use crate::flow::task::Executor;
-use crate::flow::domain::NodeDef;
-use async_trait::async_trait;
+
+#[derive(Default)]
+pub struct ScriptRhaiTask;
 
 fn truncate_str(s: &str, max: usize) -> String {
     let s = s.replace('\n', " ").replace('\r', " ");
@@ -80,9 +86,6 @@ fn read_node_script_file(ctx: &Value, node_id: &str) -> Option<String> {
     None
 }
 
-#[derive(Default)]
-pub struct ScriptRhaiTask;
-
 #[async_trait]
 impl Executor for ScriptRhaiTask {
     async fn execute(&self, node_id: &NodeId, _node: &NodeDef, ctx: &mut Value) -> anyhow::Result<()> {

backend/src/flow/executors/variable.rs

@@ -1,10 +1,12 @@
+// third-party
 use async_trait::async_trait;
 use serde_json::{Value, json};
 use tracing::info;
 
-use crate::flow::task::Executor;
+// crate
 use crate::flow::domain::{NodeDef, NodeId};
 use crate::flow::engine::eval_rhai_expr_json;
+use crate::flow::task::Executor;
 
 #[derive(Default)]
 pub struct VariableTask;