feat: add basic UI scenes (card, hand, training room, main menu)

src/ui/components/card_node.gd

@@ -0,0 +1,37 @@
+extends Control
+
+signal card_clicked(card_node)
+signal card_double_clicked(card_node)
+
+var card_data: Card = null
+var is_selected: bool = false
+
+@onready var texture_rect: TextureRect = $TextureRect
+@onready var label: Label = $Label
+
+func setup(card: Card) -> void:
+	card_data = card
+	update_display()
+
+func update_display() -> void:
+	if card_data == null:
+		return
+	var suits := ["S", "H", "C", "D", "SJ", "BJ"]
+	var ranks := ["", "", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A", "SJ", "BJ"]
+	var suit := card_data.suit()
+	var rank := card_data.rank()
+	if rank < ranks.size() and suit < suits.size():
+		label.text = "%s %s" % [suits[suit], ranks[rank]]
+	modulate = Color.WHITE if not is_selected else Color(1.2, 1.2, 0.8)
+
+func set_selected(sel: bool) -> void:
+	is_selected = sel
+	update_display()
+
+func _on_gui_input(event: InputEvent) -> void:
+	if event is InputEventMouseButton:
+		if event.button_index == MOUSE_BUTTON_LEFT and event.pressed:
+			if event.double_click:
+				card_double_clicked.emit(self)
+			else:
+				card_clicked.emit(self)