Avatar Reel Composer

Orchestrates the sibling skills into one finished reel from a script + an existing avatar, replicating the structure of the avatar's analyzed reels. An optional finishing pass (finish_reel.py) adds burned-in word-timed subtitles + a music bed under the voice — flat by default, or a structured volume envelope (entrance / lift / settle / duck / resolve, anchored to scene boundaries) that makes the soundtrack do editing work. SFX stingers and dissolves are still deferred (see Next phases).