Migrate to a Cloudflare Worker

[MattIPv4]

Type of Change

• Routes: No routes should have changed.
• Utilities: Utilities were updated to support new framework (hono).
• Tests: Tests were refactored to use Miniflare.
• Something else: Express replaces with Hono (for Cloudflare Workers).

What issue does this relate to?

N/A

What should this PR do?

Replaces the Express server that powers the API with Hono, which will allow the API to be run as a Cloudflare Worker.

Updates all the routes and utilities to run through Hono, and updates the test suite to use Miniflare.

Updates documentation in the repository to reflect that the API is now a Cloudflare Worker, including development + deployment information.

Introduces GitHub Actions workflows for automatic Cloudflare Worker deployments based on staging + production branches.

What are the acceptance criteria?

All tests pass without any material changes to them, API can be run successfully as a Cloudflare Worker.