feat(backend): initial setup and auth routes

[j-chad]

Description

Adds an axum powered backend with swagger + authentication using PASETO tokens

Related Issue

Closes #4, #3, #2 and #1

Proposed Changes

• Adds a rust backend using:
  • diesel for database
  • axum for web server
  • utoipa for documentation

Testing Done

Tested in the swagger ui

Checklist

• I have tested my changes locally and they work as expected.
• I have documented any new or modified functionality in the project documentation.
• I have added appropriate comments to the code, especially in complex or non-obvious sections.