Background task re-pushes the current color at ~timeout/2 (clamped
0.5-30s) while the light is on, so the server's idle timer never
expires and the strip stays at the picked color instead of reverting
to fallback_color.
Drops the length: 9999 magic value from segment payloads now that the
server defaults length to the remainder of the strip — requires the
matching server change in led-grab.
alexei.dolgolyov
ca5b0a8014