refactor: govern background job lifecycle

app/tools/run_preservation_runtime.py

@@ -32,17 +32,22 @@ def main() -> None:
     from server import RequestHandler, SERVICE
 
     server = ThreadingHTTPServer(("127.0.0.1", args.port), RequestHandler)
-    print(
-        f"Preservation runtime is running at http://127.0.0.1:{args.port} "
-        f"with database {SERVICE.database.path}",
-        flush=True,
-    )
     try:
+        if hasattr(SERVICE, "start_background_jobs"):
+            SERVICE.start_background_jobs()
+        print(
+            f"Preservation runtime is running at http://127.0.0.1:{args.port} "
+            f"with database {SERVICE.database.path}",
+            flush=True,
+        )
         server.serve_forever()
     except KeyboardInterrupt:
         pass
     finally:
-        SERVICE._background_stop.set()
+        if hasattr(SERVICE, "stop_background_jobs"):
+            SERVICE.stop_background_jobs()
+        else:
+            SERVICE._background_stop.set()
         server.server_close()