Get Item Page For Retrieval

Any page of a scan, for somebody about to pull that envelope by hand.

Frederick, 2026-09-02: "For transcribing an envelope, we only show the envelope, not the contents. For doing a parcel return, we should show the full contents because it makes it easier for the technician to identify the parcel and contents. They can match the envelope, match the handwriting, match the color of the paper. All that information is data for them to find a parcel in a box full of paper of other parcels."

⛔THE PIECE MUST BE ONE WE ARE ACTUALLY RETURNING, AND THAT IS CHECKED HERE RATHER THAN ASSUMED. Without this guard the route is "read anyone's correspondence" wearing a retrieval route's clothes -- the exact shape this build refuses elsewhere. An OPEN return or locate card against this item is the proof, so the permission expires when the job is done rather than lasting forever.

⛔AND IT IS A DIFFERENT ROUTE FROM /scan, NOT A FLAG ON IT. render_envelope_sides still exists, still returns two faces, and is still what every model sees. Nothing a reader can reach changed.