feat: add day/night cycle and visual workplace props

DayNightCycle.gd smoothly rotates DirectionalLight3D and interpolates sky colors, ambient light, fog, and procedural sky material across a configurable 240-second cycle with warm sunset/sunrise peaks and deep night ambiance. No simulation dependency — purely visual.

JajceWorld.tscn now includes visible workplace structures replacing the invisible Marker3Ds: wooden pantry crate, guard tower post, study desk, and rest bench. Each has a distinct material color matching the profession palette.

The DayNightCycle node is added to JajceWorld.tscn with node_paths wired to DirectionalLight3D and WorldEnvironment. Script reference uses path-based ext_resource (uid generation deferred to editor first load).

world/jajce/day_night_cycle.gd

@@ -0,0 +1,122 @@
+extends Node
+
+@export var cycle_duration_seconds := 240.0
+@export var directional_light: DirectionalLight3D
+@export var world_environment: WorldEnvironment
+
+const TO_RAD := PI / 180.0
+
+const DAY_SKY_TOP := Color(0.23, 0.43, 0.62, 1)
+const DAY_SKY_HORIZON := Color(0.82, 0.68, 0.5, 1)
+const DAY_GROUND_BOTTOM := Color(0.12, 0.17, 0.12, 1)
+const DAY_GROUND_HORIZON := Color(0.62, 0.55, 0.42, 1)
+const DAY_AMBIENT := Color(0.91, 0.85, 0.72, 1)
+const DAY_AMBIENT_ENERGY := 0.7
+const DAY_FOG_LIGHT := Color(0.82, 0.78, 0.66, 1)
+const DAY_FOG_LIGHT_ENERGY := 0.72
+const DAY_FOG_DENSITY := 0.002
+const DAY_LIGHT_COLOR := Color(1, 0.87, 0.72, 1)
+const DAY_LIGHT_ENERGY := 1.45
+
+const NIGHT_SKY_TOP := Color(0.04, 0.04, 0.12, 1)
+const NIGHT_SKY_HORIZON := Color(0.08, 0.06, 0.14, 1)
+const NIGHT_GROUND_BOTTOM := Color(0.02, 0.02, 0.04, 1)
+const NIGHT_GROUND_HORIZON := Color(0.04, 0.03, 0.06, 1)
+const NIGHT_AMBIENT := Color(0.12, 0.14, 0.28, 1)
+const NIGHT_AMBIENT_ENERGY := 0.25
+const NIGHT_FOG_LIGHT := Color(0.1, 0.12, 0.24, 1)
+const NIGHT_FOG_LIGHT_ENERGY := 0.3
+const NIGHT_FOG_DENSITY := 0.005
+const NIGHT_LIGHT_COLOR := Color(0.22, 0.28, 0.5, 1)
+const NIGHT_LIGHT_ENERGY := 0.3
+
+const SUNSET_LIGHT_COLOR := Color(1, 0.55, 0.3, 1)
+const SUNRISE_LIGHT_COLOR := Color(1, 0.6, 0.45, 1)
+const SUNRISE_SUNSET_ENERGY := 0.8
+
+var elapsed := 0.0
+
+
+func _process(delta: float) -> void:
+	elapsed += delta
+	if elapsed >= cycle_duration_seconds:
+		elapsed = fmod(elapsed, cycle_duration_seconds)
+	var cycle := elapsed / cycle_duration_seconds
+	_apply_light_rotation(cycle)
+	_apply_environment(cycle)
+
+
+func _apply_light_rotation(cycle: float) -> void:
+	if directional_light == null:
+		return
+	var angle_rad: float = cycle * 2.0 * PI
+	directional_light.rotation = Vector3(-PI / 4.0 + sin(angle_rad) * PI / 4.0, angle_rad, 0)
+
+
+func _apply_environment(cycle: float) -> void:
+	if directional_light == null:
+		return
+
+	var day_factor := _day_factor(cycle)
+	var night_factor := 1.0 - day_factor
+
+	directional_light.light_color = _lerp_color(NIGHT_LIGHT_COLOR, DAY_LIGHT_COLOR, day_factor)
+	directional_light.light_energy = lerpf(NIGHT_LIGHT_ENERGY, DAY_LIGHT_ENERGY, day_factor)
+
+	var sunset_peak := _sunrise_sunset_weight(cycle)
+	if sunset_peak > 0.0:
+		var sunset_color: Color
+		if cycle < 0.5:
+			sunset_color = SUNSET_LIGHT_COLOR
+		else:
+			sunset_color = SUNRISE_LIGHT_COLOR
+		directional_light.light_color = directional_light.light_color.lerp(
+			sunset_color, sunset_peak * 0.85
+		)
+		directional_light.light_energy = maxf(
+			directional_light.light_energy, SUNRISE_SUNSET_ENERGY * sunset_peak
+		)
+
+	if world_environment == null or world_environment.environment == null:
+		return
+
+	var env: Environment = world_environment.environment
+
+	env.ambient_light_color = _lerp_color(NIGHT_AMBIENT, DAY_AMBIENT, day_factor)
+	env.ambient_light_energy = lerpf(NIGHT_AMBIENT_ENERGY, DAY_AMBIENT_ENERGY, day_factor)
+
+	env.fog_light_color = _lerp_color(NIGHT_FOG_LIGHT, DAY_FOG_LIGHT, day_factor)
+	env.fog_light_energy = lerpf(NIGHT_FOG_LIGHT_ENERGY, DAY_FOG_LIGHT_ENERGY, day_factor)
+	env.fog_density = lerpf(NIGHT_FOG_DENSITY, DAY_FOG_DENSITY, day_factor)
+
+	var sky: Sky = env.sky
+	if sky != null and sky.sky_material is ProceduralSkyMaterial:
+		var mat: ProceduralSkyMaterial = sky.sky_material
+		mat.sky_top_color = _lerp_color(NIGHT_SKY_TOP, DAY_SKY_TOP, day_factor)
+		mat.sky_horizon_color = _lerp_color(NIGHT_SKY_HORIZON, DAY_SKY_HORIZON, day_factor)
+		mat.ground_bottom_color = _lerp_color(NIGHT_GROUND_BOTTOM, DAY_GROUND_BOTTOM, day_factor)
+		mat.ground_horizon_color = _lerp_color(NIGHT_GROUND_HORIZON, DAY_GROUND_HORIZON, day_factor)
+
+
+func _day_factor(cycle: float) -> float:
+	if cycle < 0.15:
+		return 0.0
+	if cycle < 0.3:
+		return smoothstep(0.15, 0.3, cycle)
+	if cycle < 0.7:
+		return 1.0
+	if cycle < 0.85:
+		return 1.0 - smoothstep(0.7, 0.85, cycle)
+	return 0.0
+
+
+func _sunrise_sunset_weight(cycle: float) -> float:
+	if cycle < 0.15:
+		return smoothstep(0.05, 0.15, cycle) * (1.0 - smoothstep(0.1, 0.15, cycle))
+	if cycle > 0.85:
+		return smoothstep(0.85, 0.95, cycle) * (1.0 - smoothstep(0.9, 0.95, cycle))
+	return 0.0
+
+
+func _lerp_color(from: Color, to: Color, weight: float) -> Color:
+	return from.lerp(to, clampf(weight, 0.0, 1.0))