feat(get-user): expose Hamkar menu icon brand colors

Emit menu_icon_color and menu_icon_active_color when brandManaged so apps can theme nav icons separately.

Co-authored-by: Cursor <cursoragent@cursor.com>

prisma/backfill-appearance-from-registry.ts

@@ -212,6 +212,8 @@ async function main() {
         primaryColor: primary,
         secondaryColor: secondary,
         backgroundColor: background,
+        menuIconColor: existingUi?.brand?.menuIconColor ?? null,
+        menuIconActiveColor: existingUi?.brand?.menuIconActiveColor ?? null,
         settingsManaged: managed,
         brandManaged,
         registryMode: registryMode || existingUi?.registryMode || 'dynamicMode',