Expose a per-post fediverse_creator frontmatter field plus a site-wide
default in config.toml ([site].fediverse_creator). The handle is returned
in the post and site payloads, rendered as <dc:creator> in the RSS feed
and as authors[].name in the JSON feed, so a front-end can drop it into
<meta name="fediverse:creator"> on rendered pages. Per-post value
overrides the site default. Validated against a simple @user@host regex.
Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
petrbalvinandQwen-Coder