Initial commit

Half-baked state. Most of the UI is mostly done, but the integration
with Grist (or any other data provider) is still missing.

article_select_button.gd

@@ -0,0 +1,21 @@
+extends Node
+
+@export var info: ArticleInfo
+
+signal product_selected(id: String)
+
+func _on_button_pressed() -> void:
+	product_selected.emit(info.id)
+	
+func update_info():
+	$VBoxContainer/Label.text = info.text
+	$VBoxContainer/TextureRect.texture = info.icon
+	
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	update_info()
+	product_selected.connect(Global._on_product_selected)
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+	pass