2-Way Event Dispatching

Currently Bolt Express only provides type-safe handlers for Frontend to Sandbox messaging. We’d like to add type-safe Sandbox to Frontend messaging as well for listening to Express Document events.

Example: 

<img width="513" height="571" alt="Image" src="https://github.com/user-attachments/assets/b1ec9aa1-3c06-46dd-9a58-9a5bcf00176b" />