M1b: survival stats, day/night, fire fuel, cooking, foraging, torches, death + grave

- Health, stamina, hunger, warmth and wet with HUD bars, status tags and clock
- 20-minute day/night cycle with moon, stars and lit clouds
- Campfire fuel (2 min start, 15 min max), heat radius, cooking needs a lit fire
- Berry bushes (regrow 10 min), mushrooms, roasted mushroom, torch
- Stamina costs for sprint, jump and harvest hits
- Death respawns at island start and leaves a grave bag
- Saves include stats, time of day, fire fuel, regrowth timers and graves
- New test_survival_stats suite; tests fail if a script error aborts them

scripts/player/survival.gd

@@ -0,0 +1,127 @@
+extends Node
+## Survival stats: health, stamina, hunger (satiety) and warmth, each 0..100.
+##
+## - Hunger drains over about a day and a quarter, faster when you're cold.
+## - Warmth moves toward a target: air temperature (day/night, altitude),
+##   plus heat from fires and a held torch, minus being wet.
+## - Health drains while starving or freezing, and regenerates when fed and warm.
+## - Stamina pays for sprinting, jumping and swinging, and regenerates after a
+##   short pause.
+##
+## step(dt) holds all the rules, so tests can fast-forward time. In M2 this runs
+## on the server.
+
+signal changed
+signal died
+
+const MAX := 100.0
+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
+
+var health := MAX
+var stamina := MAX
+var hunger := MAX            ## satiety: 100 = full, 0 = starving
+var warmth := 70.0
+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 player: CharacterBody3D
+var world: Node3D
+var _stamina_wait := 0.0
+
+func _process(delta: float) -> void:
+	if world != null and not world.menu_mode:
+		step(delta)
+
+func step(dt: float) -> void:
+	if dead:
+		return
+	var p := player.global_position
+	heat = world.heat_at(p)
+	var target: float = world.air_warmth(p) + 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
+	target = clampf(target, 0.0, MAX)
+	# Warm up faster than you cool down: getting to a fire should feel good.
+	warmth = move_toward(warmth, target, (7.0 if target > warmth else 1.6) * dt)
+
+	hunger = maxf(hunger - HUNGER_DRAIN * dt * (1.5 if warmth < 30.0 else 1.0), 0.0)
+
+	if _stamina_wait > 0.0:
+		_stamina_wait -= dt
+	else:
+		stamina = minf(stamina + STAMINA_REGEN * dt, MAX)
+
+	var dmg := 0.0
+	if hunger <= 0.0:
+		dmg += 0.6
+	if warmth < 12.0:
+		dmg += 0.5
+	if dmg > 0.0:
+		health = maxf(health - dmg * dt, 0.0)
+	elif hunger > 40.0 and warmth > 35.0:
+		health = minf(health + 0.5 * dt, MAX)
+
+	_update_statuses()
+	changed.emit()
+	if health <= 0.0:
+		dead = true
+		died.emit()
+
+func _update_statuses() -> void:
+	statuses.clear()
+	if heat > 0.25:
+		statuses.append("Warm")
+	if warmth < 12.0:
+		statuses.append("Freezing")
+	elif warmth < 30.0:
+		statuses.append("Cold")
+	if hunger <= 0.0:
+		statuses.append("Starving")
+	elif hunger < 25.0:
+		statuses.append("Hungry")
+	if wet > 0.0:
+		statuses.append("Wet")
+
+## Spends stamina for an action. Returns false (and spends nothing) if you're
+## too tired. Continuous costs (sprinting) pass `partial = true`.
+func use_stamina(amount: float, partial: bool = false) -> bool:
+	if stamina <= 0.0 or (not partial and stamina < amount * 0.5):
+		return false
+	stamina = maxf(stamina - amount, 0.0)
+	_stamina_wait = STAMINA_DELAY
+	return true
+
+func eat(food: Dictionary) -> void:
+	hunger = minf(hunger + float(food.get("hunger", 0)), MAX)
+	health = minf(health + float(food.get("health", 0)), MAX)
+	changed.emit()
+
+func soak() -> void:
+	wet = WET_SECONDS
+
+func reset_after_death() -> void:
+	dead = false
+	health = 50.0
+	stamina = MAX
+	hunger = 50.0
+	warmth = 60.0
+	wet = 0.0
+	changed.emit()
+
+func to_data() -> Dictionary:
+	return {"health": health, "stamina": stamina, "hunger": hunger, "warmth": warmth, "wet": wet}
+
+func load_data(d: Dictionary) -> void:
+	health = float(d.get("health", health))
+	stamina = float(d.get("stamina", stamina))
+	hunger = float(d.get("hunger", hunger))
+	warmth = float(d.get("warmth", warmth))
+	wet = float(d.get("wet", 0.0))
+	dead = false
+	changed.emit()