Move a scene to a different position in the primary lane. Positions are 0-based, so to_index 0 makes it the opening scene. Scene start times are DERIVED from order, so every scene after the move shifts in time. With ripple_secondary "shift" (the default) every clip, caption and sticker that sits wholly inside a scene moves with that scene; one that spans a scene edge stays put and is listed in straddling_ids. "none" moves the scenes alone. Refuses a shift that moves a clip on a locked track (unlock it with lock_track, or pass ripple_secondary "none") or lands a moved clip over one that stays put (pass ripple_secondary "none", or move or split that clip first).