Extend dprint from a shared remote config and add the prettier
and exec plugins, formatting TOML via a new tombi.toml instead
of golangci-lint fmt. Taskfile.yml, scripts/build.sh, and
html_styles.css pick up the resulting reformat.
Exporter examples now write to a temp dir and clean up after
themselves instead of leaving output.md/.docx/.html in the
repo. Drop the stray internal/exporters/output.docx and ignore
internal/exporters/output.* going forward.
