feat: ML-DSA-65, did:key, named hash algorithm, model provenance, log tiles and witnesses

- hashing.algorithm names the hash function in every document; a consumer refuses one it does not implement (doc.hash.algorithm)
- ML-DSA-65 (FIPS 204) is an implemented signature scheme: pure-Python reference in tools/oracle/mldsa.py checked against NIST ACVP vectors, a receipt signed by the new roster key dana, and signature vectors for key generation and a deterministic signature
- roster keys may carry a did:key, which the validator checks against the public key (doc.roster.did), and a witness purpose for parties that cosign log checkpoints
- model provenance: a correction's author and an annotation's generator name the model with provider, version and the hashes of its weights, prompt and parameters, and where it ran
- the transparency log gains the tlog-tiles static layout (fixtures/records/log/), a project settings.log with origin, witnesses and threshold, and an acceptance rule; the fixture checkpoint is cosigned by a witness
- store.sql: roster_keys accepts cose and ml-dsa-65 and gains a did column
- spec chapters 01, 08, 11, 18, 20 and 23, the rationale, glossary, fixture, vector and tool guides updated; stress harness covers ML-DSA

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

tools/oracle/package.py

@@ -280,6 +280,8 @@ def _validate(root, store, key, rep, limit=SIZE_LIMIT):
     # Policy and hashing.
     withheld = [n["id"] for n in nodes if n.get("withheld")]
     scheme = document["hashing"]["scheme"]
+    if document["hashing"].get("algorithm") != "sha-256":
+        rep.add("doc.hash.algorithm", "document.json", "the hash algorithm is not one this validator implements")
     if document["policy"] == "full" and withheld:
         rep.add("doc.policy.withheld", "nodes.jsonl", "a full package withholds no text")
     if document["policy"] == "checks-only":
@@ -402,6 +404,11 @@ def _validate(root, store, key, rep, limit=SIZE_LIMIT):
 
     # Receipts and fidelity.
     roster = {k["id"]: k for k in data.get("roster.json", {}).get("keys", [])}
+    for k in roster.values():
+        if k.get("did") and k["scheme"] in crypto.MULTICODEC:
+            pub = R._b64(k.get("public", ""))
+            if pub is None or crypto.did_key(k["scheme"], pub) != k["did"]:
+                rep.add("doc.roster.did", k["id"], "the did:key is not the one the public key determines")
     recs = data["receipts.jsonl"]
     rorder = sorted(recs, key=lambda r: (r["at"], r["id"]))
     if rorder != recs: