Legacy matches (created before the intro-clips feature) have no role on their
clips, so per-clip prompt regen wrote fight prompts for clips 0-2 instead of
the entrance/entrance/face-off intro. Add _clip_role_fighters() which honours an
explicit role/fighters or infers from position (clip 0 = f1 entrance, clip 1 =
f2 entrance, clip 2 = referee face-off, rest = fight). _fill_clip_prompt() now
uses it and PERSISTS the resolved role/fighters onto the clip so the subsequent
keyframe regen and render apply the correct profiles + LoRAs.

Also make a regenerated prompt authoritative for keyframe generation: clear any
stale kf_prompt override when (re)writing a clip prompt (keyframes compose from
the clip prompt unless an override exists, which would silently win). Same for
outcomes — _plan_outcome_shots now drops o['kf_prompt'] so regenerated outcome
prompts feed the outcome keyframes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>