Add federated room detail page and improve address parsing in invites

src/pages/RoomDetail.jsx

@@ -216,7 +216,9 @@ export default function RoomDetail() {
 
   const handleFedInvite = async (e) => {
     e.preventDefault();
-    if (!fedAddress.includes('@')) {
+    // Accept @user@domain or user@domain — must have a domain part
+    const normalized = fedAddress.startsWith('@') ? fedAddress.slice(1) : fedAddress;
+    if (!normalized.includes('@') || normalized.endsWith('@')) {
       toast.error(t('federation.addressHint'));
       return;
     }