The gateway keeps one PairingStore per served profile, but every
`/api/pairing` endpoint built the global one. An operator managing a named
profile saw the wrong pending list, and approving wrote a grant into a
whitelist their running gateway never consults — the user stays locked out
while the UI shows them as approved.
`_pairing_store(profile)` now resolves per profile and validates the name
(400/404 on an unknown one). No `_profile_scope` needed: PairingStore
resolves the profile's home itself, so nothing process-global is swapped
across an await.
Both GUIs had to change to match. The listing rides the query param — for
the dashboard that meant deleting `pairing` from the "machine-global, must
NOT be rewritten" exclusion list, a comment this change makes false. The
mutating endpoints read the profile off the BODY, which no query-param
rewrite reaches, so approve/revoke send it explicitly on both surfaces.
