Add CI workflow, API docs step, and flake metadata
Runs the suite on every push through the flake dev shell, so CI and a local checkout build with the same pinned Zig and the same reuse. The test job checks formatting and REUSE compliance before building the tests in Debug, ReleaseSafe and ReleaseFast: the first two keep the safety checks that the decoder's bounds properties lean on, while ReleaseFast drops them and can behave differently. A docs job publishes the generated API reference to https://jeff.ocj.page/zuucode/ , gated on the tests passing and on the default branch so that neither a red build nor a pushed branch can replace the live site. Building it needs a `docs` step, which emits autodoc as a side effect of building a library. The workflow lives under .forgejo/ rather than .github/ because this repository is hosted on Forgejo, whose Actions implementation reads the same syntax. Also fills in the flake description and renames the dev shell, which had kept the name of the project this flake was copied from. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MXGhGpSNDfzzwtBZc4aRvM