Wire the new ``?download=true`` resubmit endpoint into the Inbox
page. Operators can now ask the backend for a ZIP of regenerated
837s straight from the rejected-claims bulk action, with the
``X-Cyclone-Serialize-Errors`` header surfaced as a non-blocking
warning so partial successes don't swallow per-claim failures.
* ``src/lib/inbox-api.ts``: new ``resubmitRejectedWithDownload``
helper returning ``{blob, filename, serializeErrors}`` so callers
can hand the bundle to the new ``downloadBlob`` utility without
re-parsing headers.
* ``src/lib/download.ts``: new ``downloadBlob(blob, filename)`` plus
a test covering the extension/content-type mapping and the
"use the suggested filename when present" rule.
* ``src/pages/Inbox.tsx``: rejected-claims bulk action now exposes
a "Resubmit & download" button next to the existing JSON path,
wired through the helper. Conflicts and per-claim serialize
errors render in the existing toast/result surface.
Tests: 4 new download.ts tests, 5 inbox-api tests (including
serialize-errors header parsing).
Nora
Tyler