feat(library): show playtime per platform on game detail

Hero and library card show the set total. Fall back to the
row's own minutes when the API sends no total.

src/components/GameHeroCard.jsx

@@ -76,7 +76,7 @@ export default function GameHeroCard({game, auditor, profileStyle, onCorrect, on
                     <div className="mt-3 flex flex-wrap gap-2">
                         <Badge variant="secondary" className="tabular-nums">
                             <Clock className="size-3"/>
-                            {t('GAME_DETAIL.PLAYTIME', {time: formatPlaytime(game.playtimeMinutes)})}
+                            {t('GAME_DETAIL.PLAYTIME', {time: formatPlaytime(game.totalPlaytimeMinutes ?? game.playtimeMinutes)})}
                         </Badge>
                         <ComingBadge game={game}/>
                         <GameStatusBadge status={game.status}/>