When multiple Android devices join a keygen session nearly simultaneously,
the last joiner may miss the session_started gRPC event because it's sent
before the device has fully set up its event subscription.
This fix adds a 2-second delayed polling check after join to detect if
the session has already started. If the session is in_progress and we
haven't started keygen yet, trigger it via polling instead of relying
solely on the session_started event.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hailin
c3d5da46f7
