Replace the per-account toggle switch and nested manage row with a single
trailing overflow (⋮) menu holding both account-level actions:
- "Enable all" / "Disable all" — toggle every calendar in the group
- "Manage in app" (synced) / "Add calendar" (local)
The dropdown is styled to fit: rounded corners, a distinct floating
surface (surfaceContainerLowest + lifted shadow) so it stands clear of
the cards, and a divider separating the two actions. Shortened the manage
label to "Manage in app" and dropped the now-unused account a11y strings.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>