fix: open the dedicated Reddit Chat host

extensions/reddit-session-exporter/session-export.js

@@ -1,4 +1,5 @@
 const REDDITBOT_SESSION_FILENAME = 'redditbot-session.json';
+export const REDDIT_CHAT_URL = 'https://chat.reddit.com/';
 
 export function normalizeRedditAccountId(accountId) {
   const trimmed = String(accountId ?? '').trim();