Add IBAN validation using iban.js library

Implemented optional IBAN validation for the account form profile:
- Installed iban.js package for robust IBAN validation
- Added Zod validation with IBAN.isValid() for format checking
- Normalizes IBAN (removes spaces, uppercase) before storage
- Validates country-specific formats and checksums
- Added validation error messages in English and Croatian

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/lib/actions/userProfileActions.ts

@@ -10,6 +10,7 @@ import { IntlTemplateFn } from '@/app/i18n';
 import { getTranslations, getLocale } from "next-intl/server";
 import { revalidatePath } from 'next/cache';
 import { gotoHomeWithMessage } from './navigationActions';
+import * as IBAN from 'iban';
 
 export type State = {
     errors?: {
@@ -29,7 +30,17 @@ const FormSchema = (t: IntlTemplateFn) => z.object({
     firstName: z.string().optional(),
     lastName: z.string().optional(),
     address: z.string().optional(),
-    iban: z.string().optional(),
+    iban: z.string()
+        .optional()
+        .refine(
+            (val) => {
+                if (!val || val.trim() === '') return true;
+                // Remove spaces and validate using iban.js library
+                const cleaned = val.replace(/\s/g, '').toUpperCase();
+                return IBAN.isValid(cleaned);
+            },
+            { message: t("iban-invalid") }
+        ),
 });
 
 /**
@@ -73,6 +84,9 @@ export const updateUserProfile = withUser(async (user: AuthenticatedUser, prevSt
 
     const { firstName, lastName, address, iban } = validatedFields.data;
 
+    // Normalize IBAN: remove spaces and convert to uppercase
+    const normalizedIban = iban ? iban.replace(/\s/g, '').toUpperCase() : null;
+
     // Update the user profile in MongoDB
     const dbClient = await getDbClient();
     const { id: userId } = user;
@@ -82,7 +96,7 @@ export const updateUserProfile = withUser(async (user: AuthenticatedUser, prevSt
         firstName: firstName || null,
         lastName: lastName || null,
         address: address || null,
-        iban: iban || null,
+        iban: normalizedIban,
     };
 
     await dbClient.collection<UserProfile>("users")