PS 5.1 on Chinese Windows reads non-BOM files as the system ANSI codepage
(GBK), so UTF-8 Chinese bytes corrupt parsing and surface as
'Missing expression after comma' at param blocks. Adding EF BB BF BOM forces
PS 5.1 to interpret as UTF-8. Affects one_click_start.ps1 (the .cmd entry),
bootstrap_windows.ps1, start_backend.ps1, setup_backend.ps1,
start-backend-pipeline-gui.ps1, and the release scripts.