Sort the scripts and scenes into folders

main/ holds the main window and top bar, quiz/ the quiz and its parts,
player/ the music player, popups/ every popup and what they share, data/ the
songs, players, playlist and settings, server/ the MusicServer client,
common/ the list row and GameLog, and themes/ the themes and style boxes.

popups/qr_popup.gd

@@ -0,0 +1,29 @@
+class_name QRPopup
+extends BasePopup
+## Shows a QR code with the address of the search page on the MusicServer, so players
+## can search for soundtracks on their phones.
+
+@onready var qr_panel: Panel = $QRPanel
+@onready var qr_code_rect: QRCodeRect = %QRCodeRect
+@onready var url_label: Label = %URLLabel
+
+
+func _ready() -> void:
+	qr_code_rect.light_module_color = Color.WHITE
+	qr_code_rect.dark_module_color = Color.BLACK
+	qr_code_rect.quiet_zone_size = 4
+
+	# Generate QR code for the search URL
+	var url: String = Settings.default_path + "/search"
+	qr_code_rect.data = url
+	url_label.text = qr_code_rect.data
+	GameLog.debug("QR code generated for: ", url)
+
+
+func open() -> void:
+	super()
+	# Regenerate QR code in case settings changed
+	var url: String = Settings.default_path + "/search"
+	qr_code_rect.data = url
+	url_label.text = qr_code_rect.data
+