P2 stone: stonecutter, cut stone, stone floors/walls/pillars/stairs/windows/doorway, hearth; wooden stairs, windows, posts, palisade and gate; stone support rules

scripts/building/hearth.gd

@@ -0,0 +1,21 @@
+extends "res://scripts/building/campfire.gd"
+## Stone hearth: an indoor fire (docs/PROGRESSION_DESIGN.md §3). Everything a
+## campfire does (fuel, cooking, keeping wolves off), but it warms a bigger
+## room (1.5x the radius), its chimney keeps the rain off so it never burns
+## faster in a storm, and its stone doesn't need a floor of its own.
+
+const HEARTH_RADIUS := HEAT_RADIUS * 1.5
+
+func display_name() -> String:
+	return "Stone Hearth"
+
+func heat_at(pos: Vector3) -> float:
+	if not _lit:
+		return 0.0
+	return 1.0 - smoothstep(2.0, HEARTH_RADIUS, pos.distance_to(global_position))
+
+func burn_rate() -> float:
+	return 1.0
+
+func interact_prompt(player: Node) -> String:
+	return super.interact_prompt(player).replace("Campfire", "Stone hearth")