Increase pageSize to 500 for artist API calls

Fetch up to 500 tracks/albums per page instead of 50, reducing
the number of API calls needed when checking artists with large
discographies.

internal/monitor/monitor.go

@@ -137,7 +137,7 @@ func (m *Monitor) checkArtist(ctx context.Context, artistID int) {
 // checkArtistTracks checks for new tracks from an artist
 func (m *Monitor) checkArtistTracks(ctx context.Context, artistID int, artistName string) {
 	page := 0
-	pageSize := 50
+	pageSize := 500
 
 	for {
 		tracks, err := m.yandexClient.GetArtistTracks(ctx, artistID, page, pageSize)
@@ -175,7 +175,7 @@ func (m *Monitor) checkArtistTracks(ctx context.Context, artistID int, artistNam
 // checkArtistAlbums checks for new albums from an artist
 func (m *Monitor) checkArtistAlbums(ctx context.Context, artistID int, artistName string) {
 	page := 0
-	pageSize := 50
+	pageSize := 500
 
 	for {
 		albums, err := m.yandexClient.GetArtistAlbums(ctx, artistID, page, pageSize)