tests/feature_matrix.nu cargo-checks all 13 supported feature combinations and requires them error- and warning-free. fixes: - bare indexer / featureless: control/stream engine+types re-export gated (inner #![cfg] removed in favor of declaration-site cfg), Config::default ephemeral fields now cfg(not(relay)), is_pending fallback covers featureless, types/event gated to streaming modes - firehose-diagnostics: FirehoseSourceStats::snapshot visibility - relay: dead imports removed, indexer-only imports gated correctly, RepoState::synced gated any(test, relay) - unused re-exports and test-only items (LATEST_VERSION) tightened