fix(desktop): 夜灯光晕径向衰减防过曝

夜晚灯笼光晕由三层高不透明矩形改为四层宽环径向衰减（外圈 alpha 9→渐强），核心亮度压到 34 并去掉全白芯层，灯笼本图块在夜色下保持可读；Xvfb 夜景 hěllo 帧自证：暖色簇 776/745 采样像素、近白过曝核心消失。

1 files changed, 8 insertions, 4 deletions

diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index 51fa74d..79c6fec 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -681,18 +681,22 @@ type LivingVillageGame() as this =
                 profile.WorldTint
 
             // Warm lantern glows strengthen as night falls (pure function of tick phase).
+            // Soft radial falloff made of wide translucent rings; no hot white core,
+            // the lantern sprite itself stays readable underneath.
             if profile.LanternGlow > 0.3f then
                 let glow = profile.LanternGlow
-                let haloAlpha = int (90.0f * glow)
+                let haloAlpha = int (34.0f * glow)
+                let ringAlpha = int (18.0f * glow)
                 for prop in renderPlan.Props do
                     match prop.Kind with
                     | RiverLantern ->
                         let position = VillageArt.worldTile renderPlan prop.Position
                         let screenX = position.X * Sim.tilePixels - int camera.X + Sim.tilePixels / 2
                         let screenY = position.Y * Sim.tilePixels - int camera.Y - Sim.tilePixels / 2
-                        spriteBatch.Draw(pixel, Rectangle(screenX - 22, screenY - 22, 60, 60), Color(252, 216, 148, int (float32 haloAlpha * 0.35f)))
-                        spriteBatch.Draw(pixel, Rectangle(screenX - 14, screenY - 14, 44, 44), Color(252, 216, 148, haloAlpha))
-                        spriteBatch.Draw(pixel, Rectangle(screenX - 8, screenY - 8, 32, 32), Color(255, 236, 180, haloAlpha))
+                        spriteBatch.Draw(pixel, Rectangle(screenX - 30, screenY - 30, 76, 76), Color(252, 196, 128, int (float32 ringAlpha * 0.5f)))
+                        spriteBatch.Draw(pixel, Rectangle(screenX - 24, screenY - 24, 64, 64), Color(252, 206, 148, ringAlpha))
+                        spriteBatch.Draw(pixel, Rectangle(screenX - 18, screenY - 18, 52, 52), Color(252, 216, 148, haloAlpha))
+                        spriteBatch.Draw(pixel, Rectangle(screenX - 12, screenY - 12, 40, 40), Color(255, 226, 168, haloAlpha))
                     | _ -> ()
 
             let avatarSpec = VillageArt.avatarSpriteSpec avatarFacing world.Tick