The hub install path now reads `~/.fai/registry-token` as a
fallback when `FAI_REGISTRY_TOKEN` is unset (platform v0.10.92).
Studio now writes that file directly: a fresh operator pastes
the PAT into Settings → Registry credentials, hits Save, and
the next install attempt resolves the auth wall without any
shell or env-var setup.
The token never round-trips back into Studio after save —
status is shown only as "Configured (40 chars)" / "Not set"
with no display of the secret itself. The Clear action deletes
the file. On Unix the file is chmod-ed to 0600 (owner-only
read/write); Windows leaves the default user ACL in place.
Storage is strictly local: `~/.fai/registry-token`, never sent
to a remote service. The hint text under the field says so to
make the data flow explicit.
Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
