Initial commit — Station 0 vertical slice in progress

Includes full design documentation (ARCHITECTURE, DESIGN_NOTES, CONTENT_SPEC, PRODUCTION_NOTES)
and active Godot 4 / GDScript codebase. Core systems built: player, floor generation,
room system, enemy base, body part upgrades, run manager, save system, HUD, EventBus.

scripts/cards/card_collection.gd

@@ -0,0 +1,33 @@
+extends Node
+
+# card_id -> count owned
+var collection: Dictionary = {}
+
+# Array of { name: String, card_ids: Array[String] }
+var decks: Array[Dictionary] = []
+
+func add_card(card_id: String, count: int = 1) -> void:
+	collection[card_id] = collection.get(card_id, 0) + count
+
+func get_card_count(card_id: String) -> int:
+	return collection.get(card_id, 0)
+
+func open_pack(pack: Resource) -> void:
+	# Pack resource defines its card_ids array
+	if pack == null or not pack.get("card_ids"):
+		return
+	for card_id in pack.card_ids:
+		add_card(card_id)
+
+func create_deck(deck_name: String) -> void:
+	decks.append({ "name": deck_name, "card_ids": [] })
+
+func get_save_data() -> Dictionary:
+	return {
+		"collection": collection.duplicate(),
+		"decks": decks.duplicate(true),
+	}
+
+func load_save_data(data: Dictionary) -> void:
+	collection = data.get("collection", {})
+	decks = data.get("decks", [])