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>

spec/18-layers.md

@@ -54,7 +54,7 @@ Replies are annotations that target annotations, so discussions are threads anch
 | `crosslink` | `SpecificResource` | `source`, `selector` | That the span corresponds to a span in another document. |
 | `translation` | `TextualBody` | `language` | The span in another language. |
 | `description` | `TextualBody` | `role` | A description of a figure, panel or table for readers who cannot see it: `alt`, a short text equivalent, or `long`, a full description. |
-| `generated` | `TextualBody` | `generator` | Text a model wrote about the span; never mistaken for source. |
+| `generated` | `TextualBody` | `generator` | Text a model wrote about the span; never mistaken for source. `generator` is `{model, run}` as a correction's model author is ([11.2](11-corrections.md#112-every-correction-records)). |
 
 A textual body has a `value`, and optionally a `format` (`text/plain` or `text/markdown`) and a `language`.
 Nothing a model writes is ever stored as source text.