`filters.channelId` was settable by exactly one thing: a "?channel=" URL from a
shared view. The panel still rendered a CHANNEL card whose only control was
"remove" — a remove button for a filter the UI could not apply.
Two ways in now. The panel gets a real Channel group (searchable picker,
first-class alongside date/tags/language, so the chip row surfaces it for free);
normalizeLayout appends it to saved layouts, so nobody loses their arrangement.
And a subscribed channel's page gets "Show in my feed", which applies the filter
and keeps the rest of your filters — the point is "this channel, the way I
normally read", which the channel page itself can't answer (it runs show=all,
scope=all over the whole catalog).
The picker owns its channel query so a few-hundred-entry list loads when the
panel is actually opened, not on every feed visit, and says "showing 50 of N"
rather than quietly stopping.
Replace the full-height filter rails with one shared floating glass SidePanel
used by Feed, Plex and Playlists. Each collapses to a slim tab beside the nav;
its sections are reorderable "islands" (drag / hide / per-group collapse) with a
per-panel saved layout; the body hides its scrollbar with a soft top/bottom edge
fade. The nav rail becomes a matching floating rounded card.
- New shared SidePanel / PanelGroup / PanelGroups + useScrollFade hook.
- Generalise the feed-only sidebarLayout into a per-panel panelLayout (feed keeps
its storage key; plex/playlists get their own; persisted per account).
- Lift the Playlists rail to App level (selected playlist is now App state) so it
floats and collapses like the filter rails; remove the old CollapsedFilterRail.
- The floating top header's fixed offset accounts for the panels' margins.
peter