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/common.schema.json

@@ -318,8 +318,7 @@
           "type": "object",
           "properties": {
             "model": {
-              "type": "string",
-              "minLength": 1
+              "$ref": "#/$defs/model"
             },
             "run": {
               "type": "string",
@@ -334,6 +333,12 @@
         }
       ]
     },
+    "hashAlgorithm": {
+      "enum": [
+        "sha-256"
+      ],
+      "description": "The hash function every value of a package uses; the only value so far (spec/01 §1.3)."
+    },
     "hashing": {
       "oneOf": [
         {
@@ -341,6 +346,9 @@
           "properties": {
             "scheme": {
               "const": "plain"
+            },
+            "algorithm": {
+              "$ref": "#/$defs/hashAlgorithm"
             }
           },
           "required": [
@@ -354,6 +362,9 @@
             "scheme": {
               "const": "hmac-team"
             },
+            "algorithm": {
+              "$ref": "#/$defs/hashAlgorithm"
+            },
             "key_id": {
               "type": "string",
               "pattern": "^[0-9a-f]{16}$"
@@ -371,6 +382,9 @@
             "scheme": {
               "const": "hkdf-pages"
             },
+            "algorithm": {
+              "$ref": "#/$defs/hashAlgorithm"
+            },
             "context": {
               "type": "string",
               "minLength": 1
@@ -392,6 +406,40 @@
         }
       ]
     },
+    "model": {
+      "type": "object",
+      "description": "A model that proposed something: enough to name the weights and the instructions it ran with (spec/11 §11.2).",
+      "properties": {
+        "name": {
+          "type": "string",
+          "minLength": 1
+        },
+        "provider": {
+          "type": "string",
+          "minLength": 1
+        },
+        "version": {
+          "type": "string",
+          "minLength": 1
+        },
+        "weights": {
+          "$ref": "#/$defs/hash"
+        },
+        "prompt": {
+          "$ref": "#/$defs/hash"
+        },
+        "parameters": {
+          "$ref": "#/$defs/hash"
+        },
+        "processor": {
+          "$ref": "#/$defs/processor"
+        }
+      },
+      "required": [
+        "name"
+      ],
+      "additionalProperties": false
+    },
     "quote": {
       "type": "object",
       "properties": {