Documents the umbrella-first MVP decision (2026-05-24). This repo remains
INTENT-only until the anchoring interfaces stabilize through real product
use (in particular, after PDF selector round-trip is validated end-to-end).
Reaffirms: anchor depends only on engine; selector types in engine, selector
algorithms here.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
