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>

schemas/project.schema.json

@@ -220,6 +220,34 @@
         },
         "stages": {
           "$ref": "common.schema.json#/$defs/key"
+        },
+        "log": {
+          "type": "object",
+          "description": "The project's transparency log (spec/23): its origin, the roster keys that witness it, and how many must cosign a checkpoint.",
+          "properties": {
+            "origin": {
+              "type": "string",
+              "pattern": "^[^\\n]+$",
+              "minLength": 1
+            },
+            "witnesses": {
+              "type": "array",
+              "items": {
+                "$ref": "common.schema.json#/$defs/key"
+              },
+              "uniqueItems": true
+            },
+            "threshold": {
+              "type": "integer",
+              "minimum": 0
+            }
+          },
+          "required": [
+            "origin",
+            "witnesses",
+            "threshold"
+          ],
+          "additionalProperties": false
         }
       },
       "required": [],