Webapp v12.1.0

Adds search and notification support for Notebook channels. Also adds support for references to individual notes in Chat and Gallery channels.

Hash: 0vj.e3pcv.b712s.8vp8n.ojh7a.e0553.iv8cs.pea2o.iuscq.g7uma.auc0u

• Adds search across Notebook titles and contents.
• Adds notification support for Notebook activity.
• Adds access-controlled note previews for links shared in Chat.
• Improves Notebook channel recency-sorting and stale unread cleanup.