Verify a kry receipt

Checks a kry attestation entirely in your browser — nothing is uploaded, there is no server to trust. The verifier is a single file, verify.mjs (view its source — it is the same implementation that passes the 36-vector KRY-SPEC v1.2 conformance corpus and a 1,000,000-case differential fuzz against the reference).

A VALID verdict means the receipt's hash chain, magnitude arithmetic, tier schema and self-hash all re-derive correctly — i.e. no field was altered. It does not attest that the savings were real; that is the receipt's veracity_floor and evidence tier to disclose, not this checker to certify. The two demos load real conformance vectors (served from vectors/ — run python3 -m http.server at the repo root): a truncated chain verifies VALID standalone, because a prefix of a valid chain is itself a valid chain — only the operator's published chain-head anchor catches the dropped tail (SPEC §3.8). Same for a chain silently re-derived from genesis.