feat: implement email unsubscribe page

- Create /email/unsubscribe/[id] route with page and component
- Add share-id validation and 404 on invalid links
- Add bilingual translations (English/Croatian)
- Implement unsubscribe UI with success/error states
- Call unsubscribeTenantEmail server action on button click

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

web-app/app/[locale]/email/unsubscribe/[id]/page.tsx

@@ -0,0 +1,13 @@
+import { Suspense } from 'react';
+import EmailUnsubscribePage from './EmailUnsubscribePage';
+import { Main } from '@/app/ui/Main';
+
+export default async function Page({ params: { id } }: { params: { id: string } }) {
+    return (
+        <Main>
+            <Suspense fallback={<div className="text-center p-8">Loading...</div>}>
+                <EmailUnsubscribePage shareId={id} />
+            </Suspense>
+        </Main>
+    );
+}