Hot Module Replacement

**Is your feature request related to a problem? Please describe.**
Every time I make a change to the app, I need to restart it and lose all the state in the application. This is decreasing the development velocity.

**Describe the solution you'd like**
The app reloads automatically, with all the state intact, when a dependent file changes.

**Describe alternatives you've considered**
The current approach is to restart the app every time or add a file watcher that re-runs the main function every time.

The issue does not identify any files, tests, or entry points to inspect. Begin by locating Bubble Tea's application startup and event-loop entry points; done means dependent-file changes reload the app automatically while preserving application state.

Written by the indexing model from the issue text.