Targets page: collapse targets under a per-bot header (BotGroupHeader)
with a count chip and an "Open bot" cross-link. Receivers are hidden
by default and expand per group; non-bot types fall back to a "Direct
delivery" group. Telegram "Add receiver" now opens the EntitySelect
chat palette directly instead of an inline form — EntitySelect grew a
bindable `open` flag, `showTrigger`, and an `onclose` cancel signal.
Backup settings page: split the monolithic +page into focused panels
(BackupHero, BackupLedger, ExportPanel, ImportPanel, PendingStrip,
ScheduleCassette) and introduce a stepwise export/import flow with
category groups, secrets handling, conflict policy, and validation
gating. New i18n keys in both locales cover the bot grouping labels
and the backup step copy.
