improvement: lock databases across tabs and windows

Databases are now only usable in a single tab or window.

This is necessary due to PGlite single-user mode limitation to avoid race conditions if the user sends multiple queries from different locations. The postgres wire messages could be mixed resulting in unpredictable behaviours.

Web API features used to make it works:

sessionStorage to identify each tab/window with a unique id.
localStorage to store the locks between tabs and windows.
window.addEventListener('storage', ...) to listen to changes and synchronize each tab/window context state.
window.addEventListener('beforeunload', ...) to clear the lock if the tab or window is closed.

Demo:

https://github.com/user-attachments/assets/f8df6e3b-f270-4932-acde-fc249a0ec28d

supabase-community / database-build

improvement: lock databases across tabs and windows #130