Give the event banners a top-down night gradient so they read as lit cloth

TODO.md

@@ -961,8 +961,10 @@ scorecard source, this milestone is the actionable list.
       20 m range and a 14° cone changed the frame by **0.1/255**. Now 10 energy, 45 m, 24°, tilted 5°
       down — the aimed region goes 13.5 → 29.7 and the near pavement 3.7 → 11.7 (0–255), and the
       committed `06-night-flashlight` shot shows the beam on the steps and the NPC in front.
-- [ ] Marquee/event-banner emissive read under the Compatibility renderer: measure the banner
-      luminance against the reference night board and adjust only if it still clips.
+- [x] **Event banners read as lit cloth.** Measured flat top-to-bottom (114 → 125/255) with no
+      clipping, so the problem was not brightness but the missing gradient: four stacked strips
+      with night energies 2.6/2.2/1.8/1.4 now run 135 → 84, carried per material via `night_energy`
+      metadata so `set_night_mode` keeps the ratio. Daylight is unchanged and nothing clips.
 - [x] **Street-lamp pools.** Added a `lamp_late` shot that frames a lamp, and made the lamps
       `StreetLamp_*` so they tune apart from the sconces. Attenuation must stay 1.0 (the venue test
       requires physical falloff), so the pool comes from range and energy: 16 m/2.2 → **10 m/8.0**