Small header thumbnail showing exactly what the frame is currently
displaying -- same widget compositor /frame/image uses, handed back as
a plain PNG (image_pipeline.render_panel/render_placeholder gain an
as_png option) instead of packed native-panel bytes. New session-authed
GET /api/frames/{id}/preview exposes it; click-to-refresh plus a slow
60s poll on the frame header so it doesn't hammer Immich/calendar
sources just for a header thumbnail.
Frame name (pencil-icon inline edit) and the Photos/Calendar mode
selector now live in the page header, shared across all four per-frame
pages instead of being buried in the Configuration form -- so renaming
a frame or flipping its mode no longer requires navigating to a
specific tab first.
Calendar settings move out of a conditionally-hidden card on the
Configuration tab into their own dedicated tab (new /frames/{id}/
calendar route), visually greyed out when the frame is in Photos mode
but still fully usable so calendar settings can be configured ahead of
switching modes. Also wires the week-start setting into the UI for the
first time (the column/backend support landed earlier but had no
control anywhere).