feat: add V3 migration for engine_level and route-level snapshot columns

cameleer3-server-app/src/main/resources/db/migration/V3__engine_level_and_snapshots.sql

@@ -0,0 +1,9 @@
+-- Add engine level and route-level snapshot columns to executions table.
+-- Required for REGULAR engine level where route-level payloads exist but
+-- no processor execution records are created.
+
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS engine_level VARCHAR(16);
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS input_body TEXT;
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS output_body TEXT;
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS input_headers JSONB;
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS output_headers JSONB;