feat(flow): 新增分组执行与异步模式支持

refactor(executors): 将 Rhai 引擎评估逻辑迁移至 script_rhai 模块
docs: 添加 Flow 架构文档与示例 JSON
feat(i18n): 新增前端多语言支持
perf(axios): 优化 token 刷新与 401 处理逻辑
style: 统一代码格式化与简化条件判断

backend/src/services/flow_service.rs

@@ -301,6 +301,8 @@ async fn run_internal(
             .or_else(|| design.get("execution_mode").and_then(|v| v.as_str()))
             .unwrap_or("sync");
         exec_mode = parse_execution_mode(mode_str);
+        let bounded_limit = design.get("concurrencyLimit").and_then(|v| v.as_u64()).map(|x| x as usize);
+        let _ = bounded_limit;
         (chain_from_json, ctx)
     } else {
         let dsl = match serde_yaml::from_str::<FlowDSL>(&doc.yaml) {
@@ -344,7 +346,12 @@ async fn run_internal(
 
     // 执行
     let drive_res = engine
-        .drive(&chain, ctx, DriveOptions { execution_mode: exec_mode.clone(), event_tx, ..Default::default() })
+        .drive(&chain, ctx, DriveOptions {
+            execution_mode: exec_mode.clone(),
+            event_tx,
+            bounded_limit: if matches!(exec_mode, ExecutionMode::AsyncBounded) { design_concurrency_limit(&doc.design_json) } else { None },
+            ..Default::default()
+        })
         .await;
 
     match drive_res {
@@ -446,6 +453,16 @@ fn merge_json(a: &mut serde_json::Value, b: &serde_json::Value) {
 fn parse_execution_mode(s: &str) -> ExecutionMode {
     match s.to_ascii_lowercase().as_str() {
         "async" | "async_fire_and_forget" | "fire_and_forget" => ExecutionMode::AsyncFireAndForget,
+        "queued" | "queue" => ExecutionMode::AsyncQueued,
+        "bounded" | "parallel_bounded" | "bounded_parallel" => ExecutionMode::AsyncBounded,
         _ => ExecutionMode::Sync,
     }
+}
+
+fn design_concurrency_limit(design_json: &Option<serde_json::Value>) -> Option<usize> {
+    design_json
+        .as_ref()
+        .and_then(|d| d.get("concurrencyLimit"))
+        .and_then(|v| v.as_u64())
+        .map(|x| x as usize)
 }