Fix Mastodon widget line breaks not displaying

Added whitespace-pre-line CSS class to preserve line breaks in
Mastodon post content. Previously, newline characters were being
collapsed into single spaces by default HTML whitespace handling.

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

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

components/mastodon-feed.tsx

@@ -121,7 +121,7 @@ export function MastodonFeed() {
                   )}
 
                   {/* Content */}
-                  <p className="text-sm leading-relaxed text-slate-700 dark:text-slate-200">
+                  <p className="whitespace-pre-line text-sm leading-relaxed text-slate-700 dark:text-slate-200">
                     {truncated}
                   </p>