feat: minted keys, VRF seeds, RFC 9162 proofs, history roots, tag URIs and a transparency log

Keys (spec/02 §2.4), the rule paperstack settled on:
- A work key is a Scholar-style citation key, a hyphen and the first four
  Crockford base32 characters of SHA-256("scienting-key/1:" + identity),
  where the identity is the first of doi, arxiv, isbn, pmid, pmcid and
  openalex in same_as, else the folded title, year and family name. A
  collision lengthens the later key by two characters; a key is minted
  once and never recomputed. A document key adds .si, .v<seq> or .<type>
  for versions other than the version of record.
- Every fixture key is now minted (hale2026harmonic-damb,
  okafor2025solvent-acth, writer2027fixed-ynr7.v3, tiny2026tiny-j4qm), so
  every node and record ID was re-minted and the docs rewritten to match.
  The validator checks the document key against the work key and version
  (doc.key.work) and the hash part against the identifier (doc.key.suffix).
  vectors/keys.jsonl pins the cases paperstack's tests pin.

Review:
- Spot-check seeds are ECVRF-EDWARDS25519-SHA512-TAI proofs (RFC 9381),
  implemented in tools/oracle/vrf.py in plain Python and reproduced
  against the RFC's Example 16; the sample ranks by the VRF output. The
  earlier Ed25519 seed could be ground by a dishonest checker.
- RFC 9162 inclusion and consistency proofs (crypto.inclusion_path,
  verify_inclusion, consistency_proof, verify_consistency) with
  scienting-proof/1, vectors/proofs.jsonl and two fixture records.
- document.json carries `history`, the root over the corrections, with
  the empty-tree hash for none (spec/11 §11.5, rule doc.history).
- A provisional transparency log (spec/23): log entries, signed-note
  checkpoints with key hashes as transparency logs share them, the rule
  that a logged revocation beats a self-asserted time, and vectors.
- Reserved signature schemes cose and ml-dsa-65 (spec/08 §8.4).

Identifiers and text:
- urn:scienting: becomes tag:scient.ing,2026: (RFC 4151), since the URN
  namespace was never registered.
- Unicode 16.0 is pinned for normalization and categories (spec/01 §1.4);
  the checker refuses another version.

Checking:
- check.py: keys, proofs, VRF and checkpoint vectors; the proof and
  checkpoint records; a check that every ID and hash the prose quotes
  exists in the fixtures or vectors; three more broken packages
  (history-wrong, key-suffix, key-work).
- stress.py: key, VRF, proof and checkpoint properties.
- Docs: a keys section in the concepts and FAQ, rationale entries for
  keys, VRF, proofs, tag URIs and the Unicode pin, a "Looking ahead"
  section, media-type registration and OCI distribution notes.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

fixtures/records/digitization.json

@@ -1 +1 @@
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+{"axes":[{"calibration":[{"at":[90,400],"value":"1.4"},{"at":[210,400],"value":"1.6"}],"check":{"at":[150,400],"value":"1.5"},"id":"x","label":{"figure_text":"rtxzjj9","panel":"rzxn46v"},"scale":"linear","unit":"angstrom"},{"calibration":[{"at":[80,400],"value":"0"},{"at":[80,280],"value":"4"}],"id":"y","label":{"figure_text":"f31xtb6","panel":"rzxn46v"},"scale":"linear","unit":"kcal / mol"}],"confirmation":null,"dataset":"ds-hale-ctct-scan","doc":"smithlab/hale2026harmonic-damb","format":"scienting-digitization/1","id":"n43jx89tgmmzy","method":{"kind":"manual","tool":{"name":"hand","version":"0"}},"rev":12,"series":[{"id":"scan","kind":"points","legend":"scan","mark":{"color":"#285aa0","marker":"circle"},"values":[{"at":[110,360],"uncertainty":{"calibration":"0.01","marker":"0.02","resolution":"0.01","x":"0.01","y":"0.05"},"value":{"x":"1.45","y":"3.10"}},{"at":[150,330],"uncertainty":{"calibration":"0.01","marker":"0.02","resolution":"0.01","x":"0.01","y":"0.05"},"value":{"x":"1.50","y":"0.40"}},{"at":[190,300],"uncertainty":{"calibration":"0.01","marker":"0.02","resolution":"0.01","x":"0.01","y":"0.05"},"value":{"x":"1.55","y":"2.80"}}]}],"target":{"anchor":{"doc":"hale2026harmonic-damb","format":"scienting-anchor/1","kind":"panel","node":"rzxn46v","node_hash":"72ab6d60a594c2fdcb20bcc7142bd8e83d36046ef817c61d4240a93e5523e4aa","own_hash":"95cd7f9ab50d8386dc3086cf45a377c1d25c6c6111e3c422b69af10b6b1828c6","rev":12,"store":"smithlab"},"page_fp":"128d5f76c2c78ee9410c2ab4dda8abaee279db0caeec8a1cc019c3b1bd04ba60","region":[72,260,300,410],"witness":"23b6b2aaece9cb0a828a2f0265539500fcf34d5195bf720b934b8bfdeccb9834"},"verification":{"image":"41859f0385275a8386eef230d92fc34a379549dd475f27396dc6e8a94ca0fc54","max_residual":"0.9","residual":"0.4"}}