IsoPipeline now publishes refs to its currently-live NdiReceiver and NdiSender (set by RunInnerPipelineAsync, cleared on exit) so a stats poll from any thread can read FramesCaptured / FramesSent without entangling the pipeline's lifetime with its observer. The receiver's raw-frame channel is wrapped with a TappedChannelWriter so the most recent RawFrame is captured for source-resolution display, again without changing the receiver's contract.
IsoController.GetStats() drops the stub return-Empty and instead reads the live pipeline.GetStats() outside the gate so a slow stats read can't serialize the controller's other operations.
WPF: MainViewModel runs a 1 Hz DispatcherTimer that pulls stats for every participant view-model and pushes them via UpdateStats(). ParticipantViewModel grows three displayable properties — FramesIn, FramesOut, IncomingResolution — bound into the participants DataGrid as a new 'Live' column showing the down/up frame counts and the source resolution underneath the machine name.
Tests: 74/74 unit + 9/9 NDI integration green; the existing round-trip integration test exercises the new wiring at runtime (live receiver/sender refs are set, frames flow, channels close cleanly).
Adds an NdiGroupSettings record carrying optional comma-separated NDI group lists for the finder and the senders. Extends INdiInterop.CreateFinder / CreateSender with optional groups arguments and populates NDIlib_find_create_t.p_groups and NDIlib_send_create_t.p_groups via P/Invoke. IsoController reads the settings on construction, threads DiscoveryGroups into NdiDiscoveryService and OutputGroups into IsoPipelineConfig, and exposes SetGroupSettingsAsync for runtime updates (group changes apply on next process restart so live pipelines aren't orphaned).
This unblocks the 'transcoder' topology where Teams broadcasts NDI on a private group (e.g. teamsiso-input) and TeamsISO re-emits clean normalized streams on Public — keeping raw, wrong-framerate Teams sources off the production network.
EngineConfig schema is JSON-back-compat: existing config.json files (no NdiGroups field) deserialize with NdiGroups=null and load as NdiGroupSettings.Default. UI surface for these settings comes in a follow-up.
Tests: 72/72 passing (was 69) — added IsoController coverage that group settings are read from ConfigStore on startup, passed to the finder, threaded into per-pipeline config, and round-trip through SetGroupSettingsAsync/Save/Load.
