Fix per-beat layout: positions computed once for full beat set; nodes no longer move/stack between beats

Visual: SDXL illustration background + overlaid node labels (image-only mode)

Fix: storyboard beats + per-beat sync + raw Modal logging + pdf text cleaning

Visual quality: LLM xkcd diagrams + pacing fixes

Deploy Sketchnote (MiniCPM summaries + SDXL-Turbo line-art)