feat: simplify SOP to immediate-effect configuration

migrations/000010_scenario_final_result.up.sql

@@ -0,0 +1,8 @@
+ALTER TABLE scenarios
+  ADD COLUMN result_schema JSON NULL AFTER output_schema;
+
+UPDATE scenarios SET result_schema = JSON_OBJECT('fields', JSON_ARRAY());
+ALTER TABLE scenarios MODIFY result_schema JSON NOT NULL;
+
+ALTER TABLE sop_runs
+  ADD COLUMN final_result JSON NULL AFTER result;