重构: 前端DRY收口+后端测试类型对齐

- 新增 useToast composable: 消除 AiChat/Settings/Projects 4处 toast 重复
  统一默认3000ms(Projects原4000ms为操作类提示保留参数覆盖)
- 新增 utils/json.ts parseJsonArray: 消除 parseStack/parseTags/ModuleNode
  3处JSON字符串数组解析重复
- 新增 utils/html.ts escapeHtml: 消除 useMarkdown/FilePreview 2处重复
- ProjectDetail score-bar 内联三元改用 scoreTier(消除最后一处阈值硬编码)
- ConversationSidebar 删除 formatTime 透传包装(直接用 formatRelative)
- 清理死代码: parseTs/stringifyError/ErrorSink/_Unused 改私有或删除
  wrapNakedDiff 改私有(无外部 import)
- ModuleNode shortPath 改名 truncatedPath(与 useToolCard.shortPath 语义不同)

crates/df-nodes/src/human_node.rs

@@ -218,7 +218,7 @@ mod tests {
             node_id: node_id.to_string(),
             inputs: HashMap::new(),
             config,
-            execution_id: execution_id.to_string(),
+            execution_id: execution_id.into(),
             event_bus: event_bus.clone(),
             node_status: StateMachine::new(),
         }
@@ -235,7 +235,7 @@ mod tests {
     ) {
         event_bus
             .send(WorkflowEvent::HumanApprovalResponse {
-                execution_id: execution_id.to_string(),
+                execution_id: execution_id.into(),
                 node_id: node_id.to_string(),
                 decision: decision.to_string(),
                 decisions: vec![],
@@ -254,7 +254,7 @@ mod tests {
     ) {
         event_bus
             .send(WorkflowEvent::HumanApprovalResponse {
-                execution_id: execution_id.to_string(),
+                execution_id: execution_id.into(),
                 node_id: node_id.to_string(),
                 decision: String::new(),
                 decisions: decisions.iter().map(|s| s.to_string()).collect(),
@@ -477,8 +477,8 @@ mod tests {
         dag.add_node("b".to_string(), Box::new(HumanNode));
         dag.add_edge("a".to_string(), "b".to_string());
 
-        let mut executor = DagExecutor::new(bus.clone(), exec_id.to_string());
-        let sm = executor.state_machine(); // 共享状态机（spawn 后仍可读）
+        let mut executor = DagExecutor::new(bus.clone(), exec_id.into());
+        let sm = executor.state_machine(); // 共享状态机(spawn 后仍可读)
 
         let run_handle = tokio::spawn(async move {
             executor
@@ -537,7 +537,7 @@ mod tests {
         let mut dag = Dag::new();
         dag.add_node("h".to_string(), Box::new(HumanNode));
 
-        let mut executor = DagExecutor::new(bus.clone(), exec_id.to_string());
+        let mut executor = DagExecutor::new(bus.clone(), exec_id.into());
         let sm = executor.state_machine();
 
         let run_handle = tokio::spawn(async move {