On save, don't escape "+++" delimiters for alternate Hugo TOML frontmatter blocks

[edrex]

Coisas doesn't parse the alternate "+++"-delimited TOML frontmatter blocks Hugo supports for structured field editing, which is fine, but on save it escapes the delimiters, effectively unpublishing the post:

edrex/eric.pdxhub.org@4d788a3

Expected behavior: leave the delimiters in place and unescaped.

Could also teach the field editor to parse/serialize to TOML, but maybe best not to encourage divergence from Jekyll YAML since it kind of breaks the ecosystem.

[fiatjaf]

I think it's good to parse it, and other ways of inserting metadata into documents too, if possible.