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>

sql/store.sql

@@ -8,8 +8,9 @@ CREATE TABLE roster_keys (
   id VARCHAR(128) NOT NULL,
   person TEXT NOT NULL,
   role VARCHAR(16) NOT NULL CHECK (role IN ('owner', 'editor', 'reader', 'guest')),
-  scheme VARCHAR(16) NOT NULL CHECK (scheme IN ('ed25519', 'ssh', 'gpg', 'sigstore')),
+  scheme VARCHAR(16) NOT NULL CHECK (scheme IN ('ed25519', 'ssh', 'gpg', 'sigstore', 'cose', 'ml-dsa-65')),
   public_key TEXT NOT NULL,
+  did VARCHAR(128),
   purposes TEXT NOT NULL,
   registered_at VARCHAR(20) NOT NULL,
   revoked_at VARCHAR(20),