feat(dashboard): playtime chart, recently played and a playing hint

The dashboard shows the playtime of the last 30 days and Steam's recently
played games. The detail page offers to set a backlog game to Playing when
Steam reports recent playtime; unsaved edits in the backlog card stay.

src/pages/GameDetail.jsx

@@ -11,6 +11,7 @@ import {cn} from '@/lib/utils';
 import BacklogCard from '../components/BacklogCard.jsx';
 import GameCover from '../components/GameCover.jsx';
 import GameStatusBadge from '../components/GameStatusBadge.jsx';
+import PlayingHint from '../components/PlayingHint.jsx';
 import {formatPlaytime} from '../utils/games.js';
 import useSessionExpired from '../hooks/useSessionExpired.js';
 
@@ -142,7 +143,10 @@ export default function GameDetail() {
                         </div>
                     </Card>
 
-                    <BacklogCard key={data.appid} game={data} onSaved={(entry) => setData((d) => ({...d, ...entry}))}/>
+                    <PlayingHint game={data} onChanged={(entry) => setData((d) => ({...d, ...entry}))}/>
+
+                    <BacklogCard key={data.appid} game={data}
+                                 onSaved={(entry) => setData((d) => ({...d, ...entry}))}/>
 
                     {!data.hasAchievements && (
                         <Card className="items-center py-10 text-center text-sm text-muted-foreground">