Mention-style post links not opening in chat

When sharing a mention-style link (e.g. @improve the search) in chat, it doesn’t open correctly, while a regular hyperlink to the same post works as expected.

Steps to reproduce:

1. Send a mention-style post link (e.g. @post-name) in chat.

2. Click it - URL starts with “undefined“

3. Send a normal hyperlink (https://feedback.featurebase.app/p/post-name) - works fine.

Expected behavior:
Mention-style links should open the referenced post just like regular links.