ChatPeerListCoordinator, ChatComposerCoordinator, ChatOutgoingCoordinator,
and GeoChannelCoordinator complete the migration; every coordinator now
depends on a narrow @MainActor context protocol. GeoChannelCoordinator's
three injected closures collapse into a weak context. New intent op
recordPublicActivity(forChannelKey:) keeps lastPublicActivityAt
single-writer. 15 new mock-context tests; flaky-poll deadline in the
gift-wrap dedup test raised for parallel load.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
