Refactor password validation regex for consistency across application

- Updated password validation regex in ChangePasswordCommandValidator, RegisterCommandValidator, RegisterForm, and ChangePasswordForm to use Unicode property escapes for uppercase letters, ensuring consistent validation rules across both backend and frontend components.

frontend/src/features/settings/ChangePasswordForm.tsx

@@ -15,7 +15,7 @@ const schema = z.object({
   newPassword: z
     .string()
     .min(8)
-    .regex(/^(?=.*[A-Z])(?=.*[0-9]).+$/),
+    .regex(/^(?=.*\p{Lu})(?=.*\d).+$/u),
 })
 
 type FormValues = z.infer<typeof schema>