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>

fixtures/records/checkpoint.json

@@ -1 +1 @@
-{"format":"scienting-checkpoint/1","note":"scient.ing/log/smithlab\n9\nSsjq+QpCQnva7PfGTdEv1jcArj1AORP4mYfN+rLz268=\n\n— ana dBv7wspe8vvwH61eTw3SQfa3udWjBNSV0xVCxfoLhiuei/SytzSotCBOK8CvPK3scJ8xHEAnUROdAmyXAh65xchq2g0=\n","origin":"scient.ing/log/smithlab","root":"4ac8eaf90a42427bdaecf7c64dd12fd63700ae3d403913f89987cdfab2f3dbaf","signatures":[{"key_hash":"741bfbc2","name":"ana","value":"yl7y+/AfrV5PDdJB9re51aME1JXTFULF+guGK56L9LK3NKi0IE4rwK88rexwnzEcQCdRE50CbJcCHrnFyGraDQ=="}],"size":9}
+{"format":"scienting-checkpoint/1","note":"scient.ing/log/smithlab\n9\nGa0n103p3Gl136z6XWmM92kGvsvMYGXlk+ijjX4KWiA=\n\n— ana dBv7wtCAdNnczkCO5KwtrmDvtWUVPRusBSuLPeBDQoLZi9Hm34IHuNjvnjyPEar5afNf7xqcDtokk2XZEP31uJMVuwE=\n— wit h7ghDsJGkhWLaPO7+TIZQUenslhiQh/E/TKWU4ddphpFcuylQBZM2kG/o8H1nyPfUT0MkbvnFqPFfHPH3OaN5W1EwAI=\n","origin":"scient.ing/log/smithlab","root":"19ad27d74de9dc6975dfacfa5d698cf76906becbcc6065e593e8a38d7e0a5a20","signatures":[{"key_hash":"741bfbc2","name":"ana","value":"0IB02dzOQI7krC2uYO+1ZRU9G6wFK4s94ENCgtmL0ebfgge42O+ePI8Rqvlp81/vGpwO2iSTZdkQ/fW4kxW7AQ=="},{"key_hash":"87b8210e","name":"wit","value":"wkaSFYto87v5MhlBR6eyWGJCH8T9MpZTh12mGkVy7KVAFkzaQb+jwfWfI99RPQyRu+cWo8V8c8fc5o3lbUTAAg=="}],"size":9}