The corner layout's below-video host is the portrait info panel, not a
page host: it can render only Info, plus Comments as the panel's pill on
iOS. The page editor still offered "Below Video" for every page, so
assigning Related there was accepted, stored, listed as such, and then
silently rendered in the side column.
- The Layout section gains a "Below Video" picker in corner mode:
Nothing / Info / Info and Comments (macOS offers the first two). It
writes the info/comments regions; the per-page Location section and
its strings are gone.
- PanelSettings.normalizedPages clamps regions to what the host can
render (only info/comments below, comments only together with info),
so older presets self-correct. effectiveRegion(for:) resolves the
platform-specific placement and is used by both the pages list labels
and CornerPlayerLayout, replacing its own region checks.
- The layout schematic drops the below-video block for "Nothing"; the
corner-mode footer explains the constraint.
- Tests cover the picker round-trip and the clamping.
0bfbd47882