feat(e24): pin to the comfort shelf from every card and row

S3 wires the shelf's editor. The gesture is the E10 right-click menu, so the
decision "this is comfort media" can be made where the thing is — the feed, a
Plex grid, a channel row, a playlist — rather than only on the page that lists
the shelf.

One shared piece, `components/comfortPin.tsx`: the five pin-kind constructors,
the shelf query, and ONE `ActionMenuItem` that switches Pin/Unpin honestly (and
says "not known yet" with a disabled row until the shelf has answered, since a
confident "Pin" over something already pinned is exactly the quiet lie the house
rules forbid). Surfaces that already have a row menu compose the item in
(`Playlists`, `PlaylistsRail`); the rest mount `ComfortPinMenu`.

Two structural notes:

- The feed's menu lives in `VirtualFeed`, not in `Feed` — that is the list, and
  it is also what gives the channel page the gesture for free, since it renders
  `<Feed channelScoped>` all the way down.
- Cards take `menuProps` as a FUNCTION of the row, not the built props object.
  `triggerProps` is stable across renders while its return value is not, and a
  fresh object prop would blow past `VideoCard`'s memo for every card in the
  virtualized feed on every parent render.

`DataTable` and `ChannelLayoutGrid` grow a generic `rowProps` so a channel row
answers the same gesture in both of the manager's layouts; the table stays
domain-free and never learns what a menu is.

On Home the shelf tile's menu is the whole editor: four move rows (front / left
/ right / end, reusing the playlist menu's ordering idiom) plus the unpin, over
menu rows rather than drag & drop — dragging inside a horizontal, scrolling
Carousel fights the scroll, and menu rows are keyboard-reachable for free. The
reorder is optimistic on the cached payload and re-asks the server on failure
rather than showing an order that was never accepted.

The exhausted shelf tile (a pinned channel with nothing unwatched left) is
`aria-disabled`, not `disabled`: measured in Chromium, a disabled button still
receives contextmenu and pointerdown, but it loses focus — and with it Shift+F10,
the only keyboard route to the menu it most needs.

Verified end to end in the browser against the live account: all five pin kinds,
the reorder (persisted across a reload), the unpin, and the honest Unpin label on
a resume tile that is already on the shelf.

frontend/src/components/plexCards.tsx

@@ -51,11 +51,16 @@ export function PlexPosterCard({
   onOpen,
   onInfo,
   onToggleWatched,
+  menuProps,
 }: {
   card: PlexCard;
   onOpen: () => void;
   onInfo: () => void;
   onToggleWatched: (c: PlexCard) => void;
+  /** Right-click / long-press props for the GRID's one context menu (E24 S3 — the comfort pin).
+   *  A function of the card rather than a ready-made object, so every card surface in the app takes
+   *  `menuProps={menu.triggerProps}` and reads the same at every call site. */
+  menuProps?: (c: PlexCard) => Record<string, unknown>;
 }) {
   const { t } = useTranslation();
   const inProgress = (card.position_seconds ?? 0) > 0 && card.status !== "watched";
@@ -69,6 +74,7 @@ export function PlexPosterCard({
   return (
     <div
       className="group text-left"
+      {...menuProps?.(card)}
       // content-visibility keeps off-screen posters cheap to render (smoother long-list scroll).
       style={{ contentVisibility: "auto", containIntrinsicSize: "auto 300px" } as CSSProperties}
     >