refactor(api): rename dify_graph to graphon (#34095)

api/graphon/graph/graph_template.py

@@ -0,0 +1,20 @@
+from typing import Any
+
+from pydantic import BaseModel, Field
+
+
+class GraphTemplate(BaseModel):
+    """
+    Graph Template for container nodes and subgraph expansion
+
+    According to GraphEngine V2 spec, GraphTemplate contains:
+    - nodes: mapping of node definitions
+    - edges: mapping of edge definitions
+    - root_ids: list of root node IDs
+    - output_selectors: list of output selectors for the template
+    """
+
+    nodes: dict[str, dict[str, Any]] = Field(default_factory=dict, description="node definitions mapping")
+    edges: dict[str, dict[str, Any]] = Field(default_factory=dict, description="edge definitions mapping")
+    root_ids: list[str] = Field(default_factory=list, description="root node IDs")
+    output_selectors: list[str] = Field(default_factory=list, description="output selectors")