feat(mcp): подготовить сервер и доступ к приёмке

backend/drizzle/0030_mcp_scoped_configuration_checkpoint.sql

@@ -0,0 +1,6 @@
+BEGIN;
+-- Service-owned exact read-back must survive a subsequent network probe failure.
+-- Generic after_sealed remains an array of resource snapshots.
+ALTER TABLE mcp_operation_checkpoints ADD COLUMN IF NOT EXISTS configuration_sealed text;
+ALTER TABLE mcp_operation_checkpoints ADD COLUMN IF NOT EXISTS configuration_proof text;
+COMMIT;