修复: status→enum + type alias(SMELL-P1-6)

crates/df-types/src/types.rs

@@ -26,6 +26,12 @@ pub type PluginId = String;
 pub type ExecutionId = String;
 /// 决策 ID
 pub type DecisionId = String;
+/// 节点类型(如 ai / human / ai_self_review)
+pub type NodeType = String;
+/// 任务链接类型(如 depends_on / blocks / relates_to)
+pub type LinkType = String;
+/// 工具调用类型(如 function)
+pub type ToolCallType = String;
 
 // ============================================================
 // 时间工具