stage 1 of oauth removal, switch to sanctum pat tokens

resources/js/hooks/use-initials.tsx

@@ -1,8 +1,15 @@
 import { useCallback } from 'react';
 
 export function useInitials() {
-    return useCallback((fullName: string): string => {
-        const names = fullName.trim().split(' ');
+    return useCallback((fullName?: string | null): string => {
+        if (!fullName) {
+            return '';
+        }
+
+        const names = fullName
+            .trim()
+            .split(/\s+/u)
+            .filter((segment) => segment.length > 0);
 
         if (names.length === 0) return '';
         if (names.length === 1) return names[0].charAt(0).toUpperCase();