fix: batch Zep set_ontology calls to respect 10-item API limit

Zep Graph API accepts a maximum of 10 entity types or relation types
per set_ontology request. When the LLM extracts more than 10 types,
the backend sends them all at once, causing a 400 Bad Request.

The fix batches entity_types and edge_definitions into chunks of 10
and calls set_ontology multiple times.

Fixes #631

backend/app/services/graph_builder.py

@@ -284,11 +284,27 @@ class GraphBuilderService:
                 edge_definitions[name] = (edge_class, source_targets)
         
         # 调用Zep API设置本体
+        # Zep API 限制每批次最多10个实体/关系类型
+        BATCH_SIZE = 10
+        
         if entity_types or edge_definitions:
+            entity_items = list(entity_types.items())
+            edge_items = list(edge_definitions.items())
+            
+            max_batches = max(
+                (len(entity_items) + BATCH_SIZE - 1) // BATCH_SIZE if entity_items else 0,
+                (len(edge_items) + BATCH_SIZE - 1) // BATCH_SIZE if edge_items else 0,
+                1,
+            )
+            
+            for i in range(max_batches):
+                batch_entities = dict(entity_items[i * BATCH_SIZE:(i + 1) * BATCH_SIZE]) if entity_items else None
+                batch_edges = dict(edge_items[i * BATCH_SIZE:(i + 1) * BATCH_SIZE]) if edge_items else None
+                
                 self.client.graph.set_ontology(
                     graph_ids=[graph_id],
-                entities=entity_types if entity_types else None,
-                edges=edge_definitions if edge_definitions else None,
+                    entities=batch_entities if batch_entities else None,
+                    edges=batch_edges if batch_edges else None,
                 )
     
     def add_text_batches(