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/rooms/room_data.gd

@@ -0,0 +1,9 @@
+class_name RoomData
+
+enum RoomType { START, COMBAT, ITEM, SHOP, BOSS }
+
+var type:        RoomType   = RoomType.COMBAT
+var grid_pos:    Vector2i   = Vector2i.ZERO
+var connections: Dictionary = {}   # "up"/"down"/"left"/"right" -> Vector2i
+var visited:     bool       = false
+var cleared:     bool       = false