[kbuffardi]

Summary

• add persistent, category-based editor spacing defaults for Makefiles and all other files
• add an accessible status-bar spacing dropup with selected-state and outside-click behavior
• make Monaco spacing selection authoritative by disabling content-based indentation inference and applying matching tab, indent, and insert-space options
• restrict document conversion to the explicit Apply to file action
• simplify the status-bar button label while preserving its dropup behavior

Verification

• npm run lint
• npm run build
• npm run test:e2e
• rebuilt dist/ and dist-firefox/

Closes #131