Server-side shared schema draft

[JArmandoAnaya]

A schema draft that lives on the server — composed over several sittings, shared between collaborators, and published as one version when it is ready — instead of today's model, where an unpublished class exists only inside a single browser tab's dialog session.

This was placed out of scope by decision 9 of the annotation workspace redesign (#368), the change that reworked the class system, the top bar and the objects panel. The issue exists so that the constraint it would lift is written down somewhere: that redesign's WS4 Create and add another control accumulates classes in component state for the length of one dialog session only, and closing the tab loses them.

[JArmandoAnaya]

Status correction (2026-08-07): since the draft data-loss fix merged, the accidental losses this body implies are gone. The Schema tab's draft now survives tab switches, and an active-version change under a dirty draft is announced with an explicit choice rather than overwritten silently.

What remains is exactly one loss, and it is the deliberate one: dialog-session state — the annotator's create-and-add-another accumulation — and the Schema tab's local draft still die with the browser session, by design. That end-of-session loss is the constraint this issue exists to lift. Urgency unchanged, scope unchanged.

[JArmandoAnaya]

Milestoned 0.1.0 per the default rule (Armando, 2026-08-07): everything lands in 0.1.0 unless explicitly moved.