[FEAT]: setup t3-env in the monorepo

[ixahmedxi]

https://github.com/t3-oss/t3-env is a package that gives you the ability to have typesafe, runtime-checked environment variables, this means that if an environment variable is not defined, the build errors out instead of discovering it in production like I just did with my Redis environment variables name change.

I would like to setup this package for the web app, db package and auth package so that we are sure we have the required environment variables whenever we build the application.