v2.1.0-alpha.899

Changes

• docs: list the alpha.899 additions (b8c22ea)
• fix(i18n): backup strings no longer promise a schedule (91d55b3)
• fix(#483): validate backup settings, handle archive write errors (bb6a58c)
• fix(#483): prune backups on startup, write archives under a temp name (a83be3e)
• docs: v2.0.57 release notes (77457c0)

⚠️ This is an alpha release - use at your own risk!