fix(clip): a time's error line sits in the flow, the remove button off the cut, and every player surface rings amber

- useTimecodeField holds a time field's draft for its caller, which places TimecodeError (role
  alert) in its own flow under the fields' row: it no longer lies over the crop row taking its
  clicks, runs out of the editor's card, or joins the field's <label> name.
- The editor's remove-cut buttons sit in a row under the track at their cut (trackLeft), off the
  cut's grab area, where a press drags it; RangeTrack's adornment slot is gone.
- media-focus re-points --focus to the media amber on the Plex player, the YouTube stage and every
  bg-media-chrome surface; a contract test holds each such class string to media-focus or
  media-scope, the field's focus edge to the focus token, and --color-focus to the inline theme.
- An upload's quota headline says the converted file does not fit, not "Storage full".
- DESIGN.md: the tokens paragraph says what is re-pointed where; the decision row measures all
  three colours on the chrome.

frontend/src/components/PlexPlayer.tsx

@@ -113,7 +113,7 @@ const BACK_TO_PREV_S = 3;
 // inside the window skips again (the keyboard keeps ← / → at the viewer's own step).
 // The player's menus sit on the always-dark media chrome, under white text, in every theme.
 const PLAYER_MENU =
-  "rounded-xl border border-white/15 bg-media-chrome/95 text-sm text-white shadow-2xl";
+  "rounded-xl border border-white/15 bg-media-chrome/95 media-focus text-sm text-white shadow-2xl";
 const PLAYER_ROW = "block w-full rounded-lg px-2 py-1.5 text-left hover:bg-white/10";
 // A track choice: the chosen one wears the tick in the leading slot (DESIGN "one of several"), which
 // the highlight's white text cannot wash out the way it did the accent-coloured label.
@@ -1191,7 +1191,7 @@ export default function PlexPlayer({ itemId, onClose, queue, fromStart = false }
   return createPortal(
     <div
       ref={wrapRef}
-      className="fixed left-0 top-0 z-overlay bg-black flex items-center justify-center select-none"
+      className="media-focus fixed left-0 top-0 z-overlay bg-black flex items-center justify-center select-none"
       onPointerDown={(e) => {
         pointerRef.current = e.pointerType;
       }}
@@ -1840,7 +1840,7 @@ export default function PlexPlayer({ itemId, onClose, queue, fromStart = false }
           }}
         >
           <div
-            className="my-auto w-full max-w-3xl rounded-2xl border border-white/15 bg-media-chrome/95 shadow-2xl"
+            className="my-auto w-full max-w-3xl rounded-2xl border border-white/15 bg-media-chrome/95 media-focus shadow-2xl"
             onClick={(e) => e.stopPropagation()}
           >
             <Suspense fallback={null}>