fix(clip): typed times belong to their value, and every mark on the player chrome can be seen

TimecodeField drops a draft when the value moves under it (another segment selected, a nudge), so
leaving the field never commits it to another cut; it is invalid only once offered, with a line
under it saying how to type a time. On the always-dark chrome media-scope points every focus ring
at --media-mark and errors at the new --media-danger (a light theme's accent and danger were under
3:1 there). A track whose dragged handle unmounts ends the drag on the pointer's release instead of
locking up; a remove refused while clips are queued leaves no focus to take later; each remove-cut
button names its cut and is a 24px target. DESIGN.md records the media tokens; stale comments fixed.

frontend/src/components/ClipPanel.tsx

@@ -84,15 +84,17 @@ interface Props {
 
 const NUDGE_S = 0.1;
 // How far short of the item's end a seek stops: a mark on the very end moves the player to its last
-// moment, not past it — a player put at its end ENDS (a Plex film closes, a YouTube queue steps on)
-// and takes the clip with it.
+// moment, not past it. A player put at its end ENDS, and the item counts as finished — YouTube marks
+// it watched and shows its end screen, a Plex position reads as the whole — while a mark there is only
+// a place. (The players keep themselves and the clip open at an end while one is marked; this keeps
+// the item unfinished.)
 const LAST_MOMENT_S = 0.25;
 // On the always-dark chrome the ends are white (a light theme's accent is a dark blue there, which
 // all but vanished on the bar) and the playhead amber, so an end and the playhead are never confused.
-// A focused end is ringed in amber too, as the crop frame is: the accent ring was under 3:1 there.
-// The media amber (`--media-mark`), not the theme's warn: a light theme's is dark on this bar.
+// The media amber (`--media-mark`), not the theme's warn: a light theme's is dark on this bar. Every
+// focus ring in the panel is that amber as well (media-scope re-points --focus), as the crop frame's
+// is: the theme accent's ring was under 3:1 on the chrome.
 const PLAYHEAD = "bg-media-mark";
-const END_RING = "focus-visible:outline-media-mark";
 
 export default function ClipPanel({
   src,
@@ -247,7 +249,6 @@ export default function ClipPanel({
         playhead={current}
         playheadClassName={PLAYHEAD}
         onSeek={seek}
-        handleRingClassName={END_RING}
         className="h-14 cursor-pointer rounded-md bg-white/10 text-white/45"
         background={
           <RulerTicks view={view} format={(s) => formatTimecode(s, hours).replace(/\.\d$/, "")} />