ST2110SenderStateChanged

Lifecycle state of a single sender inside an ST 2110 NMOS output device. The sender_label keys events to the configured sender; state follows the sequence below. The wire-format / destinations payload is populated only on ACTIVE so a client UI can render the negotiated transport without having to fish them out of separate IS-04/IS-05 traffic.

Sequence (per sender):

IDLE ↓ (controller PATCH master_enable=true) STARTING { sender_label } ↓ (worker finishes startChildWorkflow + Spectrum compile) ACTIVE { sender_label, destinations[], wire_pixel_format } ↓ (controller PATCH master_enable=false, or another switch) IDLE

At any point: FAILED { sender_label, reason } — config rejected (e.g. unsupported wire transport) or the activation worker crashed before reaching ACTIVE.

Mirrors the pattern of MoqRelayStateChanged.