small fixes and support $ boost sign

src/shared/notes/mentions/boost.tsx

@@ -0,0 +1,5 @@
+export function Boost({ boost }: { boost: string }) {
+  return (
+    <span className="break-words text-fuchsia-400 hover:text-fuchsia-500">{boost}</span>
+  );
+}

src/shared/notes/mentions/user.tsx

@@ -1,11 +1,12 @@
+import { memo } from 'react';
+
 import { useStorage } from '@libs/storage/provider';
 
 import { WidgetKinds, useWidgets } from '@stores/widgets';
 
 import { useProfile } from '@utils/hooks/useProfile';
-import { displayNpub } from '@utils/shortenKey';
 
-export function MentionUser({ pubkey }: { pubkey: string }) {
+export const MentionUser = memo(function MentionUser({ pubkey }: { pubkey: string }) {
   const { db } = useStorage();
   const { user } = useProfile(pubkey);
 
@@ -31,11 +32,12 @@ export function MentionUser({ pubkey }: { pubkey: string }) {
       }
       className="break-words text-fuchsia-400 hover:text-fuchsia-500"
     >
-      {user?.name ||
-        user?.display_name ||
-        user?.displayName ||
-        user?.username ||
-        displayNpub(pubkey, 16)}
+      {'@' +
+        (user?.name ||
+          user?.display_name ||
+          user?.displayName ||
+          user?.username ||
+          'unknown')}
     </span>
   );
-}
+});