SL-4: fix over-dark arena - rebalance lighting for clarity

The first pass crushed readability ('can't see anything'): dark ground x low ambient x dim sun x +12 contrast (clipped everything below midtone to black) x vignette x dark fog. Rebalanced toward legibility while keeping the dark-frontier mood: ColorAdjustments contrast 12->4 (the main fix), post-exposure 0.55->0.85, saturation 0->4; sun 0.9->1.5 cool-white; ambient intensity 0.62->1.0 with lifted cool ambient colors; vignette 0.32->0.20; ground material lifted ~18%->~28% value; fog pushed out (start 18->26, end 42->60); Core beacon range 9->13. Ground, player silhouette, Ore ring and shadows now all read; Core stays the bright cyan peak.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/_Project/Rendering/PostFX_Daylight.asset

@@ -111,7 +111,7 @@ MonoBehaviour:
     m_Value: {x: 0.5, y: 0.5}
   intensity:
     m_OverrideState: 1
-    m_Value: 0.32
+    m_Value: 0.2
   smoothness:
     m_OverrideState: 1
     m_Value: 0.4
@@ -151,10 +151,10 @@ MonoBehaviour:
   active: 1
   postExposure:
     m_OverrideState: 1
-    m_Value: 0.55
+    m_Value: 0.85
   contrast:
     m_OverrideState: 1
-    m_Value: 12
+    m_Value: 4
   colorFilter:
     m_OverrideState: 1
     m_Value: {r: 0.93, g: 0.96, b: 1, a: 1}
@@ -163,7 +163,7 @@ MonoBehaviour:
     m_Value: 0
   saturation:
     m_OverrideState: 1
-    m_Value: 0
+    m_Value: 4
 --- !u!114 &7928249266562162677
 MonoBehaviour:
   m_ObjectHideFlags: 3