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/building/campfire.gd

@@ -15,6 +15,8 @@ var _fx: Array[CPUParticles3D] = []
 var _t := 0.0
 var _noise := FastNoiseLite.new()
 var _lit := true
+var _roofed_cache := -1.0      ## -1 unknown, 0 open sky, 1 under a roof
+var _roof_timer := 0.0
 
 func _build() -> void:
 	add_to_group("station:campfire")
@@ -64,19 +66,44 @@ func interact_prompt(player: Node) -> String:
 	var has_fuel: bool = player.inventory.count("wood") + player.inventory.count("stick") > 0
 	if _lit:
 		var left := "%d:%02d" % [int(fuel) / 60, int(fuel) % 60]
-		return "Campfire (%s left)%s" % [left, "  [E] Add fuel" if has_fuel else "  (add wood or sticks)"]
+		var hiss := ", hissing in the rain" if burn_rate() > 1.2 else ""
+		return "Campfire (%s left%s)%s" % [left, hiss, "  [E] Add fuel" if has_fuel else "  (add wood or sticks)"]
 	return "Campfire (out)%s" % ("  [E] Add fuel to light" if has_fuel else "  (needs wood or sticks)")
 
 func interact(player: Node) -> void:
 	Actions.add_fuel(player, self)
 
-func _process(delta: float) -> void:
+## How much faster fuel burns right now: rain on an uncovered fire makes it
+## hiss and eat through its wood (up to 4x in a storm). A roof stops that.
+func burn_rate() -> float:
+	var w: Node = get_parent().get_parent() if get_parent() != null else null
+	if w == null or w.get("weather") == null:
+		return 1.0
+	var rain: float = w.weather.rain_at(global_position)
+	if rain <= 0.05:
+		_roofed_cache = -1.0
+		return 1.0
+	if _roofed_cache < 0.0:
+		_roofed_cache = 1.0 if w.build.roofed_at(global_position) else 0.0
+	return 1.0 if _roofed_cache > 0.5 else 1.0 + 3.0 * rain
+
+func burn(seconds: float) -> void:
 	if not _lit:
 		return
-	fuel -= delta
+	fuel -= seconds * burn_rate()
 	if fuel <= 0.0:
 		fuel = 0.0
 		_set_lit(false)
+
+func _process(delta: float) -> void:
+	if not _lit:
+		return
+	_roof_timer -= delta
+	if _roof_timer <= 0.0:
+		_roof_timer = 2.0
+		_roofed_cache = -1.0   # re-check the roof now and then (you may build one)
+	burn(delta)
+	if not _lit:
 		return
 	_t += delta
 	var f := _noise.get_noise_1d(_t * 10.0)