feat: Implement Dify LLM provider and update related configurations and tests

api/tests/test_assistants.py

@@ -438,3 +438,19 @@ class TestAssistantAPI:
         metadata = runtime_resp.json()["sessionStartMetadata"]
         assert metadata["services"]["llm"]["provider"] == "fastgpt"
         assert metadata["services"]["llm"]["appId"] == "app-fastgpt-123"
+
+    def test_dify_runtime_config_uses_dify_provider(self, client, sample_assistant_data):
+        sample_assistant_data.update({
+            "configMode": "dify",
+            "apiUrl": "https://api.dify.ai/v1",
+            "apiKey": "dify-key",
+        })
+        assistant_resp = client.post("/api/assistants", json=sample_assistant_data)
+        assert assistant_resp.status_code == 200
+        assistant_id = assistant_resp.json()["id"]
+
+        runtime_resp = client.get(f"/api/assistants/{assistant_id}/runtime-config")
+        assert runtime_resp.status_code == 200
+        metadata = runtime_resp.json()["sessionStartMetadata"]
+        assert metadata["services"]["llm"]["provider"] == "dify"
+        assert metadata["services"]["llm"]["model"] == "dify"