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/player/survival.gd

@@ -19,6 +19,8 @@ const HUNGER_DRAIN := 100.0 / 1500.0   ## full to empty in ~1.25 in-game days
 const STAMINA_REGEN := 24.0
 const STAMINA_DELAY := 1.0
 const WET_SECONDS := 90.0
+const REST_AFTER := 20.0       ## seconds sheltered by a fire before you're Rested
+const REST_SECONDS := 300.0    ## Rested: stamina regenerates 50% faster
 
 var health := MAX
 var stamina := MAX
@@ -28,6 +30,11 @@ var wet := 0.0               ## seconds of "Wet" left
 var heat := 0.0              ## 0..1 from nearby fires etc (last step)
 var statuses: Array[String] = []
 var dead := false
+var roofed := false          ## a roof overhead (rain can't reach you)
+var sheltered := false       ## roof and walls (the weather barely reaches you)
+var rested := 0.0            ## seconds of Rested left
+var _shelter_left := 0.0
+var _rest_build := 0.0
 
 var player: CharacterBody3D
 var world: Node3D
@@ -42,7 +49,23 @@ func step(dt: float) -> void:
 		return
 	var p := player.global_position
 	heat = world.heat_at(p)
-	var target: float = world.air_warmth(p) + heat * 70.0
+	_shelter_left -= dt
+	if _shelter_left <= 0.0:
+		_shelter_left = 0.25
+		roofed = world.build.roofed_at(p)
+		sheltered = roofed and world.build.enclosure_at(p) >= 0.74
+	# Rain soaks you unless there's a roof over your head.
+	if not roofed and world.weather.rain_at(p) > 0.25:
+		wet = WET_SECONDS
+	# Resting: a while by a fire with a roof and walls around you.
+	if sheltered and heat > 0.25:
+		_rest_build += dt
+		if _rest_build >= REST_AFTER:
+			rested = maxf(rested, REST_SECONDS)
+	else:
+		_rest_build = 0.0
+	rested = maxf(rested - dt, 0.0)
+	var target: float = world.air_warmth(p, sheltered) + heat * 70.0
 	if wet > 0.0:
 		target -= 22.0
 		wet = maxf(wet - dt * (3.0 if heat > 0.3 else 1.0), 0.0)   # fires dry you off
@@ -55,7 +78,7 @@ func step(dt: float) -> void:
 	if _stamina_wait > 0.0:
 		_stamina_wait -= dt
 	else:
-		stamina = minf(stamina + STAMINA_REGEN * dt, MAX)
+		stamina = minf(stamina + STAMINA_REGEN * (1.5 if rested > 0.0 else 1.0) * dt, MAX)
 
 	var dmg := 0.0
 	if hunger <= 0.0:
@@ -87,6 +110,10 @@ func _update_statuses() -> void:
 		statuses.append("Hungry")
 	if wet > 0.0:
 		statuses.append("Wet")
+	if sheltered:
+		statuses.append("Sheltered")
+	if rested > 0.0:
+		statuses.append("Rested")
 
 ## Spends stamina for an action. Returns false (and spends nothing) if you're
 ## too tired. Continuous costs (sprinting) pass `partial = true`.
@@ -105,6 +132,16 @@ func eat(food: Dictionary) -> void:
 func soak() -> void:
 	wet = WET_SECONDS
 
+## After a night's sleep: a little hungrier, dry, warm and rested.
+func after_sleep(seconds: float) -> void:
+	hunger = maxf(hunger - HUNGER_DRAIN * seconds * 0.3, 0.0)
+	wet = 0.0
+	warmth = maxf(warmth, 60.0)
+	stamina = MAX
+	rested = REST_SECONDS * 2.0
+	_update_statuses()
+	changed.emit()
+
 func reset_after_death() -> void:
 	dead = false
 	health = 50.0
@@ -115,7 +152,7 @@ func reset_after_death() -> void:
 	changed.emit()
 
 func to_data() -> Dictionary:
-	return {"health": health, "stamina": stamina, "hunger": hunger, "warmth": warmth, "wet": wet}
+	return {"health": health, "stamina": stamina, "hunger": hunger, "warmth": warmth, "wet": wet, "rested": rested}
 
 func load_data(d: Dictionary) -> void:
 	health = float(d.get("health", health))
@@ -123,5 +160,6 @@ func load_data(d: Dictionary) -> void:
 	hunger = float(d.get("hunger", hunger))
 	warmth = float(d.get("warmth", warmth))
 	wet = float(d.get("wet", 0.0))
+	rested = float(d.get("rested", 0.0))
 	dead = false
 	changed.emit()