fix(a11y): WCAG 2.1 AA fixes (#2219)

apps/client/src/components/ui/custom-avatar.tsx

@@ -16,14 +16,18 @@ interface CustomAvatarProps {
   mt?: string | number;
 }
 
-// `color.shade` pairs whose filled background meets WCAG AA (4.5:1) against
-// white text. Avoids lime/yellow/green/orange — even their dark shades have
-// weak white-text contrast.
+// `color.shade` pairs whose contrast meets WCAG AA (4.5:1) in BOTH variants:
+//   - filled: white text on the shade as bg
+//   - light:  shade as text on the color's light-bg (10% color.6 over white)
+// Avoids lime/yellow/green/orange — even their dark shades have weak
+// contrast. grape and indigo were bumped from .7 to darker shades because
+// the original picks failed: grape.7 was 4.02/3.61 (both fail) and
+// indigo.7 was 4.98/4.39 (light fails by a hair).
 const SAFE_INITIALS_COLORS: MantineColor[] = [
   "blue.8",
   "cyan.9",
-  "grape.7",
-  "indigo.7",
+  "grape.9",
+  "indigo.8",
   "pink.8",
   "red.8",
   "violet.7",