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>

schemas/common.schema.json

@@ -25,7 +25,20 @@
     "key": {
       "type": "string",
       "pattern": "^[a-z0-9][a-z0-9._-]*$",
-      "maxLength": 128
+      "maxLength": 128,
+      "description": "A store, project or source key, or a legacy document key kept as an alias."
+    },
+    "workKey": {
+      "type": "string",
+      "pattern": "^[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}$",
+      "maxLength": 128,
+      "description": "A Scholar-style part, a hyphen and the hash of the work's identity (spec/02 §2.4)."
+    },
+    "documentKey": {
+      "type": "string",
+      "pattern": "^[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}(\\.[a-z0-9][a-z0-9-]*)*$",
+      "maxLength": 128,
+      "description": "A work key, with a dotted suffix for anything other than the version of record."
     },
     "alias": {
       "type": "string",
@@ -45,8 +58,9 @@
     },
     "qualifiedKey": {
       "type": "string",
-      "pattern": "^([a-z0-9][a-z0-9._-]*/)?[a-z0-9][a-z0-9._-]*$",
-      "maxLength": 257
+      "pattern": "^([a-z0-9][a-z0-9._-]*/)?[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}(\\.[a-z0-9][a-z0-9-]*)*$",
+      "maxLength": 257,
+      "description": "A document key, optionally qualified by its store."
     },
     "datasetId": {
       "type": "string",
@@ -55,7 +69,7 @@
     },
     "address": {
       "type": "string",
-      "pattern": "^([a-z0-9][a-z0-9._-]*/)?[a-z0-9][a-z0-9._-]*#[a-z0-9][a-z0-9._-]*(@[0-9a-f]{6})?(\\[(0|[1-9][0-9]*):(0|[1-9][0-9]*)\\])?$"
+      "pattern": "^([a-z0-9][a-z0-9._-]*/)?[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}(\\.[a-z0-9][a-z0-9-]*)*#[a-z0-9][a-z0-9._-]*(@[0-9a-f]{6})?(\\[(0|[1-9][0-9]*):(0|[1-9][0-9]*)\\])?$"
     },
     "time": {
       "type": "string",
@@ -209,7 +223,9 @@
             "ed25519",
             "ssh",
             "gpg",
-            "sigstore"
+            "sigstore",
+            "cose",
+            "ml-dsa-65"
           ]
         },
         "key": {
@@ -530,7 +546,7 @@
       "properties": {
         "id": {
           "type": "string",
-          "pattern": "^urn:scienting:(key|person|software):[^ ]+$"
+          "pattern": "^tag:scient\\.ing,2026:(key|person|software):[^ ]+$"
         },
         "type": {
           "enum": [