Add user account settings page with profile management

- Add /account route with profile form (firstName, lastName, address, IBAN)
- Create UserProfile type and MongoDB users collection
- Implement server actions for getting and updating user profile
- Add Account Circle icon to PageHeader linking to /account
- Install Material UI icons for account icon
- Add form input disabling during save with loading spinner
- Add cancel button to discard changes and return home
- Add English and Croatian translations for account page
- Update locale names with flag emojis in language selector

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

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

app/[locale]/account/page.tsx

@@ -0,0 +1,37 @@
+import { FC, Suspense } from 'react';
+import { Main } from '@/app/ui/Main';
+import { AccountForm, AccountFormSkeleton } from '@/app/ui/AccountForm';
+import { getUserProfile } from '@/app/lib/actions/userProfileActions';
+import { useTranslations } from 'next-intl';
+import { getTranslations } from 'next-intl/server';
+
+const AccountPage: FC = async () => {
+    const profile = await getUserProfile();
+    const t = await getTranslations('account-page');
+
+    return (
+        <Main>
+            <div className="flex flex-col items-center">
+                <h1 className="text-2xl font-bold mb-4">{t('heading')}</h1>
+                <AccountForm profile={profile} />
+            </div>
+        </Main>
+    );
+};
+
+const Page: FC = () => {
+    return (
+        <Suspense fallback={
+            <Main>
+                <div className="flex flex-col items-center">
+                    <div className="h-8 w-48 skeleton mb-4"></div>
+                    <AccountFormSkeleton />
+                </div>
+            </Main>
+        }>
+            <AccountPage />
+        </Suspense>
+    );
+};
+
+export default Page;