Documents the obscura-render layer: how to enable it (--features render),
the CLI --screenshot and CDP Page.captureScreenshot paths, what it
renders, the architecture, and a head-to-head benchmark.
Benchmark vs headless Chrome (same page, 1280x720, warmed):
- local fixture: obscura ~0.06s/33MB vs chrome ~0.90s/195MB
- example.com: obscura ~0.10s/34MB vs chrome ~0.98s/199MB
Roughly 10-15x faster and ~6x less memory. Chrome's larger PNG on the
real page reflects that it paints text, which obscura does not yet.
