Fixes
add: move the next-section comment block past a newly appended tool
write_tool only relocated the trailing comment block — the one belonging to the following top-level section, which tomlkit parses into the physically-last tool's innermost body — when overwriting an existing tool. Appending a brand-new tool (the common ohbin add / add-gist path) left that comment stranded above the new entry and dropped the blank-line separator before the next section.
write_tool now detaches it from the current last tool and re-attaches it after the new entry on append as well.