feat(environment): add painterly skies and living meadows

tests/unit/test_day_night_presentation.gd

@@ -0,0 +1,29 @@
+extends GutTest
+
+const CYCLE := preload("res://world/jajce/day_night_cycle.gd")
+
+
+func test_sun_is_highest_at_noon_and_lights_the_ground_throughout_day() -> void:
+	var cycle := CYCLE.new()
+	var light := DirectionalLight3D.new()
+	cycle.directional_light = light
+	cycle._apply_light_rotation(0.5)
+	var noon_elevation := -light.rotation_degrees.x
+	assert_gt(noon_elevation, 45.0, "Noon should have an elevated sun, not grazing light")
+	for time in [0.15, 0.25, 0.4, 0.6, 0.75, 0.85]:
+		cycle._apply_light_rotation(time)
+		assert_lt(light.rotation_degrees.x, 0.0, "The daylight source points down toward terrain")
+		assert_lt(-light.rotation_degrees.x, noon_elevation, "The solar arc peaks at noon")
+	cycle.free()
+	light.free()
+
+
+func test_warm_transitions_overlap_dawn_and_dusk_without_persisting_at_noon() -> void:
+	var cycle := CYCLE.new()
+	for time in [0.22, 0.78]:
+		assert_gt(cycle._day_factor(time), 0.0)
+		assert_lt(cycle._day_factor(time), 1.0)
+		assert_gt(cycle._sunrise_sunset_weight(time), 0.8)
+	assert_eq(cycle._sunrise_sunset_weight(0.5), 0.0)
+	assert_eq(cycle._sunrise_sunset_weight(0.0), 0.0)
+	cycle.free()