refactor: move workflow package to dify_graph (#32844)

api/dify_graph/nodes/loop/loop_start_node.py

@@ -0,0 +1,22 @@
+from dify_graph.enums import NodeType, WorkflowNodeExecutionStatus
+from dify_graph.node_events import NodeRunResult
+from dify_graph.nodes.base.node import Node
+from dify_graph.nodes.loop.entities import LoopStartNodeData
+
+
+class LoopStartNode(Node[LoopStartNodeData]):
+    """
+    Loop Start Node.
+    """
+
+    node_type = NodeType.LOOP_START
+
+    @classmethod
+    def version(cls) -> str:
+        return "1"
+
+    def _run(self) -> NodeRunResult:
+        """
+        Run the node.
+        """
+        return NodeRunResult(status=WorkflowNodeExecutionStatus.SUCCEEDED)