feat(ans): implement @logicsrc/ans M1 — resolver + offline verifier

M1 of the ANS SDK (docs/ans-sdk.md):

- name: parse/format ans://v<semver>.<agent>.<domain>
- cbor: minimal RFC 8949 codec for the COSE_Sign1 subset
- verify/merkle: RFC 6962 leaf/node hashing, tree build, inclusion-proof
  generation + verification
- verify/es256 + cose: COSE_Sign1 build/parse, Sig_structure, ES256 (WebCrypto)
- verify/rootkeys: kid -> verifier key (JWKS entries; sumdb-note is M2)
- verify: verifyReceipt() + verifyResolution() (signature + inclusion proof +
  name binding), pure and offline
- client: AnsClient resolve/rootKeys/register/status over injectable fetch,
  with a DnsApplier hook for verify-dns

Tests (24) cover name parsing, CBOR round-trips/vectors, RFC 6962 proofs, a full
ES256+Merkle receipt round-trip with positive/negative cases, and the client
against mocked fetch. Wired into the root build script.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/ans/src/cbor.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it } from 'vitest';
+import { CborTag, decodeCbor, encodeCbor } from './cbor.js';
+
+describe('cbor codec', () => {
+  it('encodes known RFC 8949 vectors', () => {
+    expect([...encodeCbor(0)]).toEqual([0x00]);
+    expect([...encodeCbor(23)]).toEqual([0x17]);
+    expect([...encodeCbor(24)]).toEqual([0x18, 0x18]);
+    expect([...encodeCbor(1000)]).toEqual([0x19, 0x03, 0xe8]);
+    expect([...encodeCbor(-1)]).toEqual([0x20]);
+    expect([...encodeCbor(-7)]).toEqual([0x26]);
+    expect([...encodeCbor('a')]).toEqual([0x61, 0x61]);
+    expect([...encodeCbor(new Uint8Array([1, 2, 3]))]).toEqual([0x43, 0x01, 0x02, 0x03]);
+    expect([...encodeCbor([1, 2, 3])]).toEqual([0x83, 0x01, 0x02, 0x03]);
+  });
+
+  it('round-trips ints, bytes, strings, arrays, maps, tags', () => {
+    const value = new CborTag(18, [
+      new Uint8Array([0xa1, 0x01, 0x26]),
+      new Map<unknown, unknown>([
+        [4, new Uint8Array([1, 2, 3, 4])],
+        ['ans-proof', new Map<unknown, unknown>([['index', 1], ['size', 3], ['path', [new Uint8Array([9])]]])],
+      ]),
+      new Uint8Array([0xde, 0xad]),
+      new Uint8Array(64).fill(7),
+    ]);
+    const decoded = decodeCbor(encodeCbor(value as never));
+    expect(decoded).toEqual(value);
+  });
+
+  it('round-trips a large (4-byte and 8-byte) integer', () => {
+    expect(decodeCbor(encodeCbor(70000))).toBe(70000);
+    expect(decodeCbor(encodeCbor(5_000_000_000))).toBe(5_000_000_000);
+  });
+});