P73（昼夜光照层次：清晨/正午/黄昏/夜晚四档）证据分析 — 真实 Desktop xvfb 1280x720
钩子：LV_P73_SHOT=1（同一桥头光源机位，6/12/18/22 各一帧，画面差异只来自光照）
路径：tick → periodAtTick → periodLighting(环境色调/覆盖色/VeilAlpha/灯光) + 连续 blend/warmth veils

p73-morning: hour=6.0 tick=1296000 period=清晨 blend=0.2 lantern=0.32 tint=(255, 229, 212) veil=20
p73-noon: hour=12.0 tick=2592000 period=正午 blend=0.0 lantern=0.0 tint=(255, 255, 255) veil=0
p73-dusk: hour=18.0 tick=3888000 period=黄昏 blend=0.0 lantern=0.6 tint=(255, 255, 255) veil=52
p73-night: hour=22.0 tick=4752000 period=夜晚 blend=1.0 lantern=1.0 tint=(118, 136, 184) veil=26


p73-morning.png: size=1280x720 brightness=107.9 R=123.0 G=118.7 B=81.8 warmth(R-B)=+41.2 std=34.1 dark_block=0
p73-noon.png: size=1280x720 brightness=86.4 R=71.0 G=107.8 B=80.4 warmth(R-B)=-9.5 std=36.5 dark_block=0
p73-dusk.png: size=1280x720 brightness=97.8 R=113.8 G=111.5 B=68.0 warmth(R-B)=+45.8 std=39.2 dark_block=0
p73-night.png: size=1280x720 brightness=89.8 R=65.7 G=90.1 B=113.6 warmth(R-B)=-47.9 std=40.2 dark_block=0

diff p73-morning vs p73-noon: differing_pixels=905809
diff p73-morning vs p73-dusk: differing_pixels=905399
diff p73-morning vs p73-night: differing_pixels=921390
diff p73-noon vs p73-dusk: differing_pixels=905696
diff p73-noon vs p73-night: differing_pixels=921368
diff p73-dusk vs p73-night: differing_pixels=921390

brightness order: morning(107.9) > dusk(97.8) > night(89.8) > noon(86.4)
warmth order: dusk(+45.8) > morning(+41.2) > noon(-9.5) > night(-47.9)

verdict=PASS
  four periods have distinct parameters; noon identity, dusk lamps on, night lamps full;
  real frames render 1280x720, differ pairwise, night darker / noon brighter / dusk warmer.