fix: unify tier color mapping, fix feature badge colors

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/utils/tier.ts

@@ -0,0 +1,20 @@
+export type TierColor = 'primary' | 'success' | 'warning' | 'error' | 'auto';
+
+export function tierColor(tier: string): TierColor {
+  switch (tier?.toUpperCase()) {
+    case 'BUSINESS':
+    case 'ENTERPRISE':
+      return 'success';
+    case 'HIGH':
+    case 'PRO':
+      return 'primary';
+    case 'MID':
+    case 'STARTER':
+      return 'warning';
+    case 'LOW':
+    case 'FREE':
+      return 'auto';
+    default:
+      return 'auto';
+  }
+}