feat(freight): non-terminal change-request review + unified customer timeline

Backoffice can now "Request changes" on a pending settings change
request without rejecting it outright: a new ChangesRequested status
keeps the row open so the customer's next edit appends into the same
request instead of starting a fresh cycle, and the reviewer's note
persists across that round instead of being cleared on resubmit.

Version History and Review History (previously two separate,
differently-shaped lists) are merged into one chronological timeline
under a new History tab, including document changes shown as a real
previous-vs-current diff (both files openable).

Bug fixes surfaced while wiring this up:
- Replacing a single-file document slot left the old file live
  alongside the new one instead of retiring it (customer settings +
  onboarding uploads).
- The "previous" file in a document diff 404'd once superseded —
  the preview route now also matches soft-deleted records.
- A document replace was recorded twice in the timeline (once at
  upload, once again at change-request approval).

apps/edr-freight-web/backoffice/src/constants/URLS.ts

@@ -83,6 +83,8 @@ export const URL_CONSTANTS = {
       `/companies/change-requests/${id}/approve`,
     CHANGE_REQUEST_REJECT: (id: string) =>
       `/companies/change-requests/${id}/reject`,
+    CHANGE_REQUEST_REQUEST_CHANGES: (id: string) =>
+      `/companies/change-requests/${id}/request-changes`,
     DOCUMENT_REQUEST_CHANGE: (fileId: string) =>
       `/companies/documents/${fileId}/request-change`,
     BOOKINGS_CUSTOMER_VIEW: (id: string) =>