Revert "fix: readable pill text via WCAG contrast, not a luminance threshold"

This reverts commit 595d12f81b.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/RoadEvent.kt

@@ -246,7 +246,7 @@ private fun CategoryPill(
     Surface(
         modifier = modifier,
         color = color,
-        contentColor = readableOn(color),
+        contentColor = if (color.luminance() > 0.55f) Color.Black else Color.White,
         shape = RoundedCornerShape(50),
         shadowElevation = 3.dp,
     ) {
@@ -259,19 +259,6 @@ private fun CategoryPill(
     }
 }
 
-/**
- * Picks black or white — whichever has the higher WCAG contrast ratio against
- * [background]. A plain luminance threshold mis-handles mid-tone colors (e.g.
- * turquoise/gray), leaving white text barely legible; the contrast ratio does
- * not.
- */
-private fun readableOn(background: Color): Color {
-    val l = background.luminance()
-    val contrastWithBlack = (l + 0.05f) / 0.05f
-    val contrastWithWhite = 1.05f / (l + 0.05f)
-    return if (contrastWithBlack >= contrastWithWhite) Color.Black else Color.White
-}
-
 /**
  * Best available coordinate for the card map: the event's explicit `lat`/`lon`
  * tags when present, otherwise the center of the finest published geohash.