Fix Image add Content tab crash and the form close control.

[aryan7081]

Fixes #163

This issue happened because the Image add Content tab spread the full JSON Schema onto React Aria widgets, so object fields crashed the route. The image object browser then fetched /@objectBrowserWidget/@@add, which is a CMS route rather than a content path, so React Router had no result for that resource. Close did nothing on add because it linked to content['@id'], which a new item does not have yet. Save then failed because the Image field stored a URL string while createContent expects a NamedBlobImage object (data, encoding, content-type, filename).

This fix registers ImageWidget for REST API Image and file fields, forwards only a small set of widget props, maps /@@add and /@@edit to a real content path before loading the object browser, and points Close at that path (or the item @id on edit). Uploads write a NamedBlobImage payload; picking an existing image copies that file into the same shape so Save can succeed. Image scale flattening also skips missing scales/download so blob images do not take down the view.

Caution

The Volto Team has suspended its review of new pull requests from first-time contributors until the release of Plone 7, which is preliminarily scheduled for the second quarter of 2026.
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