Move the "Showing all events for <window>" line out of the picker and into
the agenda view as an always-visible header above the list. Add two
settings (Agenda group, both ON by default) to toggle the range header
banner and the bottom-left range pill independently. The picker keeps its
two-list grouping but no longer carries the header.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>