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/ui/hud.gd

@@ -147,7 +147,25 @@ func _process(_d: float) -> void:
 	_status.text = "  ".join(s.statuses)
 	var dn = player.get_parent().day_night
 	if dn != null:
-		_clock.text = dn.clock_text()
+		var wx = player.get_parent().weather
+		_clock.text = dn.clock_text() + ("   " + wx.label() if wx != null else "")
+
+## Fades to black, runs `mid` (e.g. skipping the night), and fades back in.
+func fade(mid: Callable) -> void:
+	var black := ColorRect.new()
+	black.color = Color(0, 0, 0, 0)
+	black.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	black.mouse_filter = Control.MOUSE_FILTER_STOP
+	add_child(black)
+	player.ui_open = true
+	var tw := black.create_tween()
+	tw.tween_property(black, "color:a", 1.0, 0.8)
+	tw.tween_callback(mid)
+	tw.tween_interval(0.7)
+	tw.tween_property(black, "color:a", 0.0, 1.0)
+	tw.tween_callback(func():
+		player.ui_open = false
+		black.queue_free())
 
 ## Closes the inventory / menu (e.g. on death).
 func close_screens() -> void: