feat: adds `packages/api` for a tRPC api layer.

• creates a new packages/api package that hosts a tRPC api to be used for the web application.
• renames the lucia auth getSession function to auth and provides a new uncached version of it.
• refactors the code in some places to be generally better.
• splits the utils package from a barrel export to multi-file export.
• getBaseUrl util now returns window.location.origin instead of an empty string when the window object is not undefined.