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/plexContext.ts

@@ -22,6 +22,8 @@ export type PlexJumpTarget = {
    *  from INSIDE the Plex module (the header typeahead), where the entry being replaced would be a
    *  sub-view the user really was looking at. */
   replace?: boolean;
+  /** `play` only: from the start, not the resume point (the card's Restart, C5). */
+  fromStart?: boolean;
 };
 
 export type PlexState = {