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/PlayerModal.tsx

@@ -936,7 +936,7 @@ export default function PlayerModal({
               ref={stageRef}
               // The wheel over the video is its volume, even inside a stacked card that scrolls.
               data-wheel-volume=""
-              className={`player-stage relative aspect-video w-full bg-black overflow-hidden ${
+              className={`player-stage media-focus relative aspect-video w-full bg-black overflow-hidden ${
                 wide ? (clipOpen ? "rounded-tl-2xl" : "rounded-l-2xl") : "rounded-t-2xl"
               } ${maximized ? "player-stage--max" : ""}`}
             >
@@ -1009,7 +1009,7 @@ export default function PlayerModal({
               {(maximized || isFullscreen) && !clipDocked && (
                 <div
                   onClick={(e) => e.stopPropagation()}
-                  className="absolute inset-x-0 bottom-0 z-menu flex h-14 items-center justify-start gap-x-3 overflow-x-auto border-t border-white/10 bg-media-chrome/95 px-3 text-sm text-white"
+                  className="absolute inset-x-0 bottom-0 z-menu flex h-14 items-center justify-start gap-x-3 overflow-x-auto border-t border-white/10 bg-media-chrome/95 media-focus px-3 text-sm text-white"
                 >
                   {hasQueue && (
                     <>