When the new fuel-import route started accepting .xlsx uploads, the
real xlsx MIME type (application/vnd.openxmlformats-officedocument
.spreadsheetml.sheet) hit PB's mimeTypes allowlist on data_import_
batches.original_file and got rejected with:
validation_invalid_mime_type: mime type must be one of:
application/pdf, image/jpeg, image/png, image/webp, text/csv,
text/plain, application/vnd.ms-excel, application/csv.
The old CSV-only route never hit this (text/csv was already on the
list), so the audit-trail batch attach worked fine.
Adds the OOXML xlsx MIME to the allowlist via the same migration
pattern as 2026-08-19 and 2026-08-24-fuel-logs. Idempotent: re-run
is a no-op once applied. No app-code changes - the route was
already sending the correct MIME for the file extension.
Verified: batch create succeeds against live PB with the exact
xlsx payload the route sends.