feat: add validation for Revolut profile name format

- Add ownerRevolutProfileName field validation when enableRevolutPayment is true
- Validate profile name must start with '@' and contain only letters and numbers
- Add required field validation for Revolut profile name
- Add English and Croatian error messages for validation failures
- Update State type to include ownerRevolutProfileName errors

Validation regex: /^@[a-zA-Z0-9]+$/
Valid examples: @john123, @ivan, @user2024

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

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

app/lib/actions/userSettingsActions.ts

@@ -19,6 +19,7 @@ export type State = {
         ownerTown?: string[];
         ownerIBAN?: string[];
         currency?: string[];
+        ownerRevolutProfileName?: string[];
     };
     message?: string | null;
     success?: boolean;
@@ -96,6 +97,26 @@ const FormSchema = (t: IntlTemplateFn) => z.object({
 }, {
     message: t("currency-required"),
     path: ["currency"],
+})
+.refine((data) => {
+    if (data.enableRevolutPayment) {
+        return !!data.ownerRevolutProfileName && data.ownerRevolutProfileName.trim().length > 0;
+    }
+    return true;
+}, {
+    message: t("owner-revolut-profile-required"),
+    path: ["ownerRevolutProfileName"],
+})
+.refine((data) => {
+    if (data.enableRevolutPayment && data.ownerRevolutProfileName) {
+        const profileName = data.ownerRevolutProfileName.trim();
+        // Must start with @ and contain only English letters and numbers
+        return /^@[a-zA-Z0-9]+$/.test(profileName);
+    }
+    return true;
+}, {
+    message: t("owner-revolut-profile-invalid"),
+    path: ["ownerRevolutProfileName"],
 });
 
 /**