Missing alternative text field for images

What’s broken?

When inserting an image in the Docs editor, no field allows providing alternative text. Only a caption is offered, which does not substitute for alternative text.

What did you expect to happen?

A dedicated alternative text field, distinct from the caption, must be available in the image editing panel. Its value must be reflected in the alt attribute of the generated element.

Steps to reproduce

Open a Docs document
Insert an image via / or the toolbar
Open the image editing panel
Notice that no alternative text field is available, only a caption field
Possible solution

Add an "Alternative text" field in the image editing panel, distinct from the caption field.
Additional context / Screenshots

The caption is visible content associated with the image; it does not replace alternative text, which is transmitted to assistive technologies and must describe the content or function of the image.

WCAG Criteria

Criterion 1.1: Does each informative image have alternative text?

Impact

A blind user navigating with a screen reader inserts an image and has no way to provide alternative text. The image will be rendered without accessible description for users relying on assistive technologies.

BlockNote version

0.51.4

Start at the image editing panel and follow the image insertion flow in the Docs editor. Check how the caption value reaches the generated image element, then add the separate alternative-text value and verify that it is reflected in the alt attribute without replacing the caption.