Exploration spike (#299 Phase 1): reusable PNG/JPG -> grayscale -> threshold
-> PBM -> `potrace -s` -> SVG pipeline with optional rsvg-convert render-back
for visual QA. CLI via argparse, ruff-clean. Not production wiring.
Spike verdict: Phase 1 production-ready for clean line-art (gated by an
input-quality filter); no Phase 2 ML needed yet. Median compression 1.29x,
readability 87% (100% on genuine line-art). Full doc → vault code/patterns.
Caveat: real DOM.RF validation pending the 22d SSR scraper.
