The dashboard auth registry is process-global, but a bundled auth provider
was registered under the per-home plugin manager's scope and enrolled in that
manager's reverse-order teardown. A per-home manager is unloaded routinely
(profile-scoped dashboard activity, forced re-discovery), and that teardown
disposed the registration — emptying the auth registry for the whole process
and permanently disabling sign-in until restart.
Register dashboard-auth providers in the process-global slot as persistent
host-owned registrations kept out of per-home manager teardown, so a routine
unload can no longer disable authentication process-wide. Registration upserts,
so a forced re-discovery (e.g. a password change) still rotates the provider in
place. The test-only manager reset now clears the auth registry too, since
persistent registrations deliberately survive unload.
Fixes#91701
rainbowgits
b2ade2388d