Ask for permission to read installed fonts, and register outline sources
for the faces it returns. Must be called from a user gesture — the
permission prompt requires one, and without it the call rejects.
Rejects when the API is missing or the user denies; both are ordinary
outcomes and neither leaves the registry in a partial state, so a caller
that simply ignores the rejection still has a working SDF tier.
Ask for permission to read installed fonts, and register outline sources for the faces it returns. Must be called from a user gesture — the permission prompt requires one, and without it the call rejects.
Rejects when the API is missing or the user denies; both are ordinary outcomes and neither leaves the registry in a partial state, so a caller that simply ignores the rejection still has a working SDF tier.