fix(downloads): Retry draws the refresh glyph, not Play (E28 S4)

The first UI-review run (Downloads) found a failed row whose Retry wore the
Play glyph in the row and its menu, promising a video. DESIGN.md gains
'a glyph means one thing' and a log row.

frontend/src/components/useDownloadActions.tsx

@@ -9,6 +9,7 @@ import {
   Pencil,
   Play,
   PlayCircle,
+  RefreshCw,
   RotateCcw,
   Scissors,
   Share2,
@@ -139,7 +140,7 @@ export function useDownloadActions({
               label: t(
                 job.status === "error" ? "downloads.actions.retry" : "downloads.actions.resume",
               ),
-              icon: icon(Play),
+              icon: icon(job.status === "error" ? RefreshCw : Play),
               onSelect: () => act.mutate({ id: job.id, op: "resume" }),
             },
       ],