* Forms: keep tiles and render unbaked field values during page re-render
In complex interactive forms, switching focus away from an edited field
caused its text to disappear for several seconds while background tiles
re-rendered.
- In DocView, retain existing tiles as stale rather than immediately
purging them on page_changed so the canvas remains sharp without flashing.
- Prioritize visible tiles over backdrops in the render queue.
- Track unbaked form fields and paint an immediate egui widget preview
for committed text, checkbox, and radio inputs until fresh raster
tiles arrive.
- Scope page invalidation on form edits to pages containing the edited
or calculated fields.
- Hoist fields lookup in recalculate_with and apply_changes to eliminate
repeated parsing.
- Run JavaScript scripts via catch_unwind on the current thread instead of
spawning a new thread per script invocation.
- Add contributor entry for Piohrun in contributors/people.toml.
- Add test switching_fields_keeps_committed_text_visible_immediately.
* Forms: address review feedback on tile stale tracking, hoist, and diff invalidation
- Revert crates/js to preserve dedicated 1 GiB stack thread for boa scripts.
- In DocView::page_changed, purge non-current-tag tiles and mark only current-tag tiles stale.
- Restore demand queue order in prepare_render_queue.
- Add unbaked overlay entries only on successful edit apply and only for fields whose values changed; fix font zoom calculation on 90°/270° pages.
- Re-read fields(doc) in recalculate_with only when script returns changes.
- Diff form before and after edit in apply_edit, invalidating pages with changed fields, falling back to document_changed for XFA or page-count changes.
- Add tests covering script recalculation side effects across pages, unbaked overlay cleanup on tile delivery/zoom/rejection, and checkbox recalc chaining.
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Co-authored-by: Brandon Thomas <echelon@gmail.com>
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