fix(test): api_contract_test添加 invitation_code_enabled 字段

backend/internal/server/api_contract_test.go

@@ -488,6 +488,7 @@ func TestAPIContracts(t *testing.T) {
 					"fallback_model_openai": "gpt-4o",
 					"enable_identity_patch": true,
 					"identity_patch_prompt": "",
+					"invitation_code_enabled": false,
 					"home_content": "",
 					"hide_ccs_import_button": false,
 					"purchase_subscription_enabled": false,