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>

spec/01-conventions.md

@@ -43,6 +43,9 @@ U+200B ZERO WIDTH SPACE is not whitespace.
 Stored text is kept exactly as witnessed; normalization applies only when a value is computed.
 The vectors in `normalize.jsonl` cover the cases, including the angstrom sign, which NFC turns into Å.
 
+Normalization forms, General Categories and the `White_Space` property are those of Unicode 16.0.
+A later Unicode version can change a decomposition or a category, and with it a hash, so an implementation states the Unicode version its character data comes from, the reference tools refuse to run on another, and moving the formats to a later version is a change to every format that hashes text ([0.3](00-introduction.md#03-format-identifiers-and-versions)).
+
 ## 1.5 Character offsets
 
 Offsets count Unicode code points, never UTF-16 code units or bytes.
@@ -67,7 +70,9 @@ No file carries the time it was written, unless the time is part of the record,
 | --- | --- | --- |
 | Node ID | Seven characters of lowercase Crockford base32, the first a letter. | `^[a-hjkmnp-tv-z][0-9a-hjkmnp-tv-z]{6}$` |
 | Record ID | 7 to 26 such characters, the first a letter. Derived records use 13. | `^[a-hjkmnp-tv-z][0-9a-hjkmnp-tv-z]{6,25}$` |
-| Key | A document, work, store, project or source key. At most 128 characters. | `^[a-z0-9][a-z0-9._-]*$` |
+| Work key | A Scholar-style part, a hyphen and 4 to 51 characters of Crockford base32 ([2.4](02-model.md#24-work-and-document-keys)). At most 128 characters. | `^[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}$` |
+| Document key | A work key, with a dotted suffix for a version other than the version of record. At most 128 characters. | `^[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}(\.[a-z0-9][a-z0-9-]*)*$` |
+| Key | A store, project or source key, or a legacy document key kept as an alias. At most 128 characters. | `^[a-z0-9][a-z0-9._-]*$` |
 | Alias | A legacy ID; it always holds a `.`, `_` or `-`, so it never looks like a node ID. | `^[a-z0-9][a-z0-9._-]*[._-][a-z0-9._-]*$` |
 | Dataset ID | `ds-` and a key. | `^ds-[a-z0-9][a-z0-9._-]*$` |