- master_keys.uuid (UUID v4, unique index): new keys get one on create,
existing keys once on start. It survives rotate (new secret) and
relabel, so it identifies the key itself rather than its link.
- /ui/masterkeys* and /api/v1/masterkeys* return uuid, and :id in those
paths accepts the numeric id or the uuid.
- /sub/v1 register, peek and devices return key_uuid, so a client can
recognise the same key behind a reissued link. It is not in the sen://
link (that would need a new format) and not in config, so rev and
existing clients are unaffected - checked against a 0.3.1 ui.db.
- Panel: the uuid sits in the key's row like a device ID (full value in
the tooltip, click copies) and in the key settings with a copy button;
on mobile it is shown under the key's name.
- README: uuid in the master key API.