Replace or Remove APIGen

[kevinfodness]

Description of the bug

The documentation for https://api.fieldmanager.org is produced using https://github.com/apigen/apigen. The latest stable version of apigen doesn't include support for PHP 8 features, and the latest alpha is from two years ago, so we need a suitable replacement.

Steps To Reproduce

Observe that https://github.com/apigen/apigen has not had a stable release since 2015.

Additional Information

No response

[mboynes]

Laravel has similar API docs and that uses Doctum

[mboynes]

Got this started in #887. The docs look and work great.

As an MVP, we could just merge that. But it would be far better if:

1. The docs were moved to its own branch, like a "built" branch.
2. As part of a release, a GitHub action would update the docs and commit the changes to that branch.
3. After the branch were updated, api.fieldmanager.org was updated.

[mboynes]

I closed #887 in favor of #888 and got that ball rolling, but it's not done. I did also one-time update https://api.fieldmanager.org/.

• The docs were moved to its own branch, like a "built" branch.
  • I created the api-docs branch for this.
• As part of a release, a GitHub action would update the docs and commit the changes to that branch.
  • I asked Claude to create this GitHub action. It's in that PR, but it's untested.
• After the branch were updated, api.fieldmanager.org was updated.
  • Given how (in)frequently FM is updated, I'm not sure if this is worth it, so maybe this is a manual process?

[renatonascalves]

Ops. Not sure how I assign myself into this. It was a mistake.