When a new federation link is established, announce not only LOCAL
global rooms but also rooms from OTHER peers (remote_participants).
This fixes multi-hop: when R2 connects to R3, R2 tells R3 about
R1's rooms that R2 learned about earlier.
Previously, only local rooms were announced on link setup. If R1
had a client but R2 had no clients, R2 wouldn't tell R3 about R1.
Also added diagnostic logging for room announcements on link setup.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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