Follow the GDScript style guide in every script

- Types on every parameter, return value and variable, and snake_case names
  (the player name limit is the constant MAX_NAME_LENGTH).
- Spelling fixes: *_triggered, character_selected, separator, caught_errors.
  The server's catched_errors key stays as the server sends it.
- Signals are connected with signal.connect() instead of by name.
- Code is ordered signals, constants, exported vars, vars, @onready vars,
  functions, with @onready on one line and two blank lines between functions.
- Every script starts with a ## description. Template comments, old LOC notes
  and commented-out code are gone, apart from the local play code.
- Lines are at most 100 characters, apart from the local play path.
- The screenshot tour turns off the blinking text cursor so pictures match.

qr_popup.gd

@@ -1,27 +1,25 @@
 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
+@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