Field Guide: the hub becomes an engraved frontispiece, with its own master seal + the "image is the proof" plug (#37)

* feat(field-guide): the master seal — a guilloché medallion struck from the whole catalog

The guide that says "the image is the proof" now wears its own proof. A single
large rose-engine medallion, seeded only from the catalog's verifiable record
(driver count, field notes, games, processes, blocklist refresh date), with that
record's fingerprint milled into the rim like a coin's inscription. …