feat(design): players on touch and the C5 control set, restart on the card (E28 S3f2)

Plex player: a finger's tap on the picture only shows or hides the controls,
the hide timer starts with playback, a double-tap on a side third skips 10 s,
the seek bar is a 2.75rem touch-none hit area with its head shown on touch.
The row is play/pause, Back by position, Next only with a next item, mute,
time, tracks, a fixed ⋯ (settings, media info, stats, shortcuts, download)
and fullscreen; Stop, Restart and the ±10 s buttons are gone.

A started card shows the video card's Continue + Restart pair (one shared
MediaResumeButtons, beside the picture's button), and its menu lists the
restart; the player opens that item at 0 (fromStart). YouTube modal: the
description opens from an ⓘ, the queue arrows sit inside the screen.

frontend/src/components/PlexInfo.tsx

@@ -347,7 +347,7 @@ type Props = {
   // When provided, a cast member's photo/name opens their filmography page instead of filtering.
   onOpenPerson?: (name: string) => void;
   // Play a sibling title from a collection strip (opens its player).
-  onPlayItem?: (id: string) => void;
+  onPlayItem?: (id: string, fromStart?: boolean) => void;
   // The item's library key — enables the admin "Manage collections" editor (page variant, movies).
   library?: string;
 };
@@ -720,6 +720,7 @@ export default function PlexInfo({
                       shelf
                       navIndex={i}
                       onOpen={() => onPlayItem?.(m.id)}
+                      onRestart={onPlayItem && (() => onPlayItem(m.id, true))}
                     />
                   </div>
                 ))}