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/submissions/anchor-miss.json

@@ -1 +1 @@
-{"answers":{"anchors":[{"context":{"column_path":["Set B","$K_r$ (kcal mol⁻¹ Å⁻²)"],"row_path":["Bond parameters","CT–CT"],"table_label":"Table 1"},"doc":"hale2026harmonic","format":"scienting-anchor/1","kind":"cell","node":"hw8fx4r","node_hash":"e554e4381827c90595a9083fd3a16e6cc72d0b14e52b3d86104c4b42a9f101b8","own_hash":"6356e0e8a0c4c9911e9657be9ee00e47fbe2ee6c54928d2b3d126266b19fa1e3","quote":{"exact":"305.2"},"rev":12,"store":"smithlab"}]},"doc":"smithlab/hale2026harmonic","exercise":"urn:scienting:annotation:smithlab/tj573y8mhap0f","format":"scienting-submission/1","id":"zw21e9386dtp2","rev":12,"student":"s-9q4p","submitted_at":"2026-10-20T10:00:00Z"}
+{"answers":{"anchors":[{"context":{"column_path":["Set B","$K_r$ (kcal mol⁻¹ Å⁻²)"],"row_path":["Bond parameters","CT–CT"],"table_label":"Table 1"},"doc":"hale2026harmonic-damb","format":"scienting-anchor/1","kind":"cell","node":"j6y45v6","node_hash":"00c4b92e220303ebc2bfb36aa557ac80ae4dba1675e9ed47adb82f6aeff10634","own_hash":"111d2b2cb30e3b04aff04b7de13a105a07a189d5ba97ae7d78eb7601ac99f9d9","quote":{"exact":"305.2"},"rev":12,"store":"smithlab"}]},"doc":"smithlab/hale2026harmonic-damb","exercise":"tag:scient.ing,2026:annotation:smithlab/whcypxav2cqbx","format":"scienting-submission/1","id":"ysw9hjztre498","rev":12,"student":"s-9q4p","submitted_at":"2026-10-20T10:00:00Z"}