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/inventory_screen.gd

@@ -263,6 +263,10 @@ func _recipe_row(r: Dictionary) -> Control:
 	h.add_child(b)
 	return row
 
+## Shift-click crafts up to five (handy for walls and floors).
 func _craft(recipe_id: String) -> void:
-	Actions.craft(player, recipe_id)
+	var n := 5 if Input.is_key_pressed(KEY_SHIFT) else 1
+	for i in range(n):
+		if not Actions.can_craft(player, recipe_id) or not Actions.craft(player, recipe_id):
+			break
 	_refresh()