AddProfile writes the config it builds straight to disk, but built it with
createNewConfig, which stopped generating the peer's keys when identity
generation moved out of apply() into EnsureIdentity. The profile file landed
with an empty PrivateKey and SSHKey.
Nothing lost the keys permanently — the daemon's own getConfig provisions and
persists them on first use — but every reader that does not write got a
config that cannot connect in the meantime, which is exactly the set this
branch grew: the update-settings gate deciding whether to refuse a request,
and the mobile SDKs loading a stored profile.
createProvisionedConfig exists for callers that persist or connect, and this
is one; before the split, createNewConfig produced the keys here too.