Feature: Allow adding empty comments / highlights without comment text

[NiiiNonno]

Feature Request

I would like to propose a feature that allows users to create a highlight without requiring any comment text. (The highlight is just a comment without content.)

Current Behavior

Currently, it is not possible to add an annotation/comment unless some valid text content is entered into the comment field.

Proposed Solution

If restricting empty comments was an intentional design choice, it would be great to have a setting in the options to toggle whether empty comments/highlights are permitted.

Ideally, users should be able to trigger a highlight instantaneously with a single hotkey while reading, without interrupting their reading flow to type text.

Context & Motivation

Having used web annotation services like Hypothesis, I strongly feel the usefulness of a pure highlighting feature. A highlight without accompanying text is far from meaningless:

1. Capturing Non-Verbal Insights: It allows users to record immediate emotional responses or subtle thoughts that cannot yet be easily articulated into words.
2. Instant Bookmarking: It serves as a quick visual marker for later review.
3. Maintaining Reading Speed: A crucial aspect of effective highlighting is not slowing down the reading speed. Being able to highlight instantly with a hotkey keeps the focus on reading.
4. Low-Friction Annotating: On different devices or environments where keyboard input is cumbersome, or when the user simply isn't in the mood to write, it provides a light and seamless way to annotate notes.

If this idea aligns with the project's direction, I would be happy to work on this and submit a Pull Request!