binpatch library: no config reads, no progress rendering

Stated in website/src/content/docs/architecture.md (re-stated in 2026-07-30 session as authoritative): binpatch library never reads config files — cache directory is injected via makeCache. Library never renders progress — consumers plug in their own indicator. Implication: any integration feature that requires config parsing or progress UX belongs in the consumer wrapper (e.g., the GitHub Action), not in the library core.