writeServiceState, the database backup, and the boot-service installer
fsync what they wrote and then the parent directory so an atomic rename
survives power loss. Windows breaks both halves: a handle opened read-only
cannot be flushed, and a directory handle opens but fails to sync with
EPERM. Every service-state write and every trial update therefore failed
there. Open the file read-write before syncing it and ignore EPERM on the
directory sync, which NTFS journals on its own.

Co-Authored-By: Claude Code <noreply@anthropic.com>