Connects to a running video node by host:port. Supports: enum-devices, enum-controls, get-control, set-control, start-ingest, stop-ingest Uses semaphore-based request/response synchronisation (same pattern as query_cli). start-ingest maps directly to the new START_INGEST protocol command with optional format/size/fps args; defaults to auto-select. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>