[enhancement]: Make related tab on full screen player useful

Resolves #50. Adds a new set of components for fetching similar songs
from the current playing song. For Jellyfin, use the `/items/{itemId}/similar`
endpoint (may not work well for small libraries), and for Navidrome/Subsonic
use `getSimilarSongs`. _In theory_, this component can be used to get similar
songs anywhere.

src/renderer/api/query-keys.ts

@@ -18,6 +18,7 @@ import type {
     LyricsQuery,
     LyricSearchQuery,
     GenreListQuery,
+    SimilarSongsQuery,
 } from './types';
 
 export const splitPaginatedQuery = (key: any) => {
@@ -239,6 +240,10 @@ export const queryKeys: Record<
             return [serverId, 'songs', 'randomSongList'] as const;
         },
         root: (serverId: string) => [serverId, 'songs'] as const,
+        similar: (serverId: string, query?: SimilarSongsQuery) => {
+            if (query) return [serverId, 'song', 'similar', query] as const;
+            return [serverId, 'song', 'similar'] as const;
+        },
     },
     users: {
         list: (serverId: string, query?: UserListQuery) => {