Profile redesign: Add alt to avatar and header (#38532)

app/javascript/mastodon/components/avatar.tsx

@@ -13,6 +13,7 @@ interface Props {
   account:
     | Pick<Account, 'id' | 'acct' | 'avatar' | 'avatar_static'>
     | undefined; // FIXME: remove `undefined` once we know for sure its always there
+  alt?: string;
   size?: number;
   style?: React.CSSProperties;
   inline?: boolean;
@@ -25,6 +26,7 @@ interface Props {
 
 export const Avatar: React.FC<Props> = ({
   account,
+  alt = '',
   animate = autoPlayGif,
   size = 20,
   inline = false,
@@ -65,7 +67,7 @@ export const Avatar: React.FC<Props> = ({
       style={style}
     >
       {src && !error && (
-        <img src={src} alt='' onLoad={handleLoad} onError={handleError} />
+        <img src={src} alt={alt} onLoad={handleLoad} onError={handleError} />
       )}
 
       {counter && (