goldenRefreshPeriod property

When > 0, the GOLDEN reference is refreshed once every goldenRefreshPeriod inter frames (the 1st, N+1th, 2N+1th, ... inter after a keyframe) and held constant in between, regardless of refreshGoldenOnInter. Gives the decoder a stable long-term reference for packet-loss recovery and lets motion search target a non-drifting frame on slow VC content. 0 (default) preserves the original behaviour where refreshGoldenOnInter is applied every inter frame. Mutable at runtime via setGoldenRefreshPeriod.