It seems it may have be simpler to just use 'mike'..
Additionally squashes related commits providing minor fixes + improvements:
- Use a job dependency (`needs`) to avoid `push` event race conditions due to parallel jobs.
- Improve workflow file documentation via inline comments.
- Make ShellCheck linting happy.
- `chown` doesn't seem to work unless on the default branch for CI. Opted to use the docker `--user` approach instead.
Separate workflows for `push` and `pull_request` events. This avoids a `skipped` job status (`Check Run`?) always being presented for the `deploy` job in Pull Requests.
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chore(`.gitignore`): Ignore the `docs/site/` build output
Ignore to avoid local builds output appearing in git as unstaged.
