Upload atoms now also report into an app-wide `uploadProgressAtom`, and
`aggregateUploadProgress` turns every in-flight upload into one taskbar
state: byte-weighted percentage while uploading, indeterminate until a
size is known, red after a failure (held 4 s, then cleared), none when
done. Cancelled uploads just disappear. `useTauriTaskbarProgress` sends it
to the native `set_taskbar_progress`, at most ~4 times a second, always
ending on the latest state.
Verified with a throttled 6 MB upload: 0% → 99% at 250 ms steps, then
cleared; with the upload request aborted: 0% → error → cleared after 4 s.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA
