BackupType._deleting is dead: declared, read once, never set

[Pixnop]

Declared in src/global.d.ts on BackupType, read by the backup-deletion guard, set nowhere. Its GameVersionType twin is wired properly in ListVersions.tsx. Either set it around the delete (the domain service already reads it through the snapshot, no domain change needed) or remove it.

[Zaldaryon]

Fixed by #136 (Fixes #13, merged 2026-08-18), left open by mistake since a merge into dev doesn't auto-close. ManageInstallationBackups now sets _deleting before the delete IPC call and clears it on failure, confirmed present in the current dev tree.