Render unknown URLs inside the app shell and move ListeningStats to the domain types

Add catch-all routes so unknown pages 404 inside the (app) layout and unknown
/api URLs return a JSON 404 instead of redirecting to the login page. Restore
the full root error page.

web-player/src/lib/server/mappers.ts

@@ -1,5 +1,5 @@
 import type { components } from '$lib/api/schema';
-import type { Album, LikedTrack, Mix, Paged, Playlist, Track } from '$lib/types';
+import type { Album, LikedTrack, ListeningStats, Mix, Paged, Playlist, Track } from '$lib/types';
 
 type TrackDto = components['schemas']['TrackApplicationResponse'];
 type AlbumDto = components['schemas']['AlbumApplicationResponse'];
@@ -84,12 +84,6 @@ export function toPlaylist(dto: PlaylistDto): Playlist {
 
 type ListeningStatsDto = components['schemas']['ListeningStatsResponse'];
 
-export interface ListeningStats {
-	tracksThisWeek: number;
-	secondsThisWeek: number;
-	streakDays: number;
-}
-
 export function toCount(value: number | string | null | undefined): number {
 	return Number(value ?? 0) || 0;
 }