Recipients can download a PDF that contains the inserted fields while
the envelope is in the PENDING state.
The token file route accepts the `pending` version. The PDF contains
only the fields from recipients who signed and the fields of the
recipient who makes the request. This is the same set of fields that
the signing page shows to the recipient.
The signing page and the completion page show the download dialog for
pending envelopes. The dialog does not show the "Partial" button for
legacy envelopes.
Add V2 API routes to download an envelope's certificate and audit log
separately, and align the internal cert/audit log downloads to use
envelopeId.
Enforces document visibility via getEnvelopeWhereInput and loads field
signatures so certificates render correctly.