refactor: simplify lobby server architecture and update app metadata

* remove legacy data bridge, RPC, and server bootstrap files
* simplify lobby scene and node hierarchy
* rename lobby UI scene path and update signal handlers
* replace the application icon and configure the boot splash
* add project description and version metadata

scenes/data/game_data.gd

@@ -0,0 +1,18 @@
+class_name GameData extends Node
+
+
+var game_address: String = "0.0.0.0"
+var game_port: int       = 8080
+
+
+func _init() -> void:
+	Globals.game_data = self
+
+
+@rpc("authority", "reliable")
+func set_game_address(_address: String) -> void:
+	pass
+
+@rpc("authority", "reliable")
+func set_game_port(_port: String) -> void:
+	pass