Fold daemonError into SessionAnnounceOptions so the helper owns the
mutually-exclusive choice between peer list and daemon-down hint. Before
this fix, a session-announce against an unreachable daemon emitted both
"No other mailboxes seen within the last 60 minutes (0 total registered)."
(misleading — the daemon was never asked) AND the daemon-unreachable hint.
Now only the hint appears when the daemon is down.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>