Fixes since 0.62.0-beta:
- fix loading reference link titles in read-only text notes, closes #4404
- fix content renderer of protected canvas/mermaid notes, closes #4414
- fix assigning extension to attachment export filenames, closes #4415
- Migrate KaTeX@0.16.0 from libraries to KaTeX@0.16.9 in node_modules #4417
- revert general HTML support
- change the way frontend detects content change which works even if no new blob is created, fixes #4434