Replace the deck's black interludes.

Replaces the deck's black interludes with the list given ([] removes them all; the chapters read returns the current ones as interludes). A black interlude is a beat of pure black between two chapters (0.5 to 2 seconds), keyed by the chapter it follows (afterChapterIndex), that may carry one sound (a breath, a bell) or one short line heard over the dark, the narrator's or a character's own, always as a voice-over. It costs no render: the master draws the black and voices its line and its sound at no charge. The whole list is validated: each follows a chapter the plan has and never the last one, at most one after any chapter, a line of at most 12 words, and a cast speaker who has a voice (400 otherwise). Free. On a draft plan the changed plan is queued for plan coverage again (planCoverage); in review or complete the master is re-assembled with the black, its lines and its sounds (reassembling). Refused while a render or finish pass runs (409). Requires Idempotency-Key. Scope: story:write.