M1c: weather, snap building, shelter, beds and regrowth

- Seeded weather (clear/cloudy/rain/storm, snow and blizzards on cold days
  and above the snowline), lightning, synthesised rain/wind/thunder sound
- Rain/snow particles stopped by roofs; wet ground, settled snow and wind
  via global shader uniforms
- Snap-together wood floor, wall, door, roof and gable with structural
  support, collapse and X to dismantle
- Shelter detection: dry under a roof, warmer and Rested inside with a fire;
  rain burns an uncovered campfire faster
- Bed sets the spawn point and lets you sleep through the night
- Trees, boulders and ground pickups regrow; timers saved
- Grass cleared under floors; shorter HUD hint
- New test_weather_building suite (62 checks) and tests/run_all.sh, which
  also fails on script errors

scripts/world/resource_node.gd

@@ -29,6 +29,11 @@ var rng := RandomNumberGenerator.new()
 
 var _shake := 0.0
 var _shake_axis := Vector3.RIGHT
+var _stump: MeshInstance3D
+var _orig_shapes: Array = []        ## [CollisionShape3D, shape, position] before the stump
+
+## Emitted when a player fells or mines this (not when a save restores it).
+signal depleted_now(node: Node)
 
 func display_name() -> String:
 	return "Tree" if kind == "tree" else "Boulder"
@@ -107,7 +112,36 @@ func _deplete(from: Vector3, animate: bool = true) -> void:
 	else:
 		if animate:
 			_burst(global_position + Vector3(0, 0.8, 0), chip_color, 40)
-		queue_free()
+		# Kept (hidden, no collision) so it can regrow later.
+		set_process(false)
+		remove_from_group("harvestable")
+	if animate:
+		depleted_now.emit(self)
+
+## Brings a felled tree or mined boulder back, growing in over a few seconds.
+func regrow() -> void:
+	if not depleted:
+		return
+	depleted = false
+	hp = max_hp
+	if _stump != null:
+		_stump.queue_free()
+		_stump = null
+	for e in _orig_shapes:
+		e[0].shape = e[1]
+		e[0].position = e[2]
+	_orig_shapes.clear()
+	if has_meta("is_stump"):
+		remove_meta("is_stump")
+	collision_layer = 1
+	add_to_group("harvestable")
+	set_process(true)
+	if is_inside_tree() and DisplayServer.get_name() != "headless":
+		var tw := create_tween()
+		tw.tween_method(func(k: float): _set_instance(Transform3D(base_xf.basis.scaled_local(Vector3.ONE * k), base_xf.origin)),
+			0.15, 1.0, 4.0).set_trans(Tween.TRANS_SINE)
+	else:
+		_set_instance(base_xf)
 
 func _fell(from: Vector3, animate: bool) -> void:
 	var world := get_parent()
@@ -139,9 +173,11 @@ func _make_stump(world: Node) -> void:
 	stump.material_override = stump_material
 	world.add_child(stump)
 	stump.global_position = base_xf.origin
+	_stump = stump
 	# Keep collision as a short stump.
 	for c in get_children():
 		if c is CollisionShape3D and c.shape is CapsuleShape3D:
+			_orig_shapes.append([c, c.shape, c.position])
 			var cyl := CylinderShape3D.new()
 			cyl.radius = (c.shape as CapsuleShape3D).radius
 			cyl.height = 0.6