feat(Notebook): enable HTML mode toggle for article notes

[rbarbazz]

Context

I use omnivore-ai-annotations to generate article summaries in markdown. Reading summaries in Omnivore is sub-optimal as:

• The markdown displays in a small, non-resizable text-area.
• There is no option to toggle between markdown and HTML views.

Solution

Enable the "mode-toggle" plugin in the markdown editor. This plugin allows users to toggle between writing and reading modes, similar to Obsidian. I also increased the editor's height for article notes for a better reading experience.

Feedback appreciated 🙏

Note: I was unable to run the content fetching service locally (see https://github.com/omnivore-app/omnivore/issues/4269) and didn't test my changes with highlights.

Screenshots

Markdown	HTML