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/upgrades/body_part_pickup.gd

@@ -0,0 +1,11 @@
+extends Area2D
+
+var part: BodyPartData = null
+
+func _ready() -> void:
+	body_entered.connect(_on_body_entered)
+
+func _on_body_entered(body: Node) -> void:
+	if body.is_in_group("player") and part != null:
+		UpgradeManager.acquire_part(part)
+		queue_free()