Switch manifest serialization to CBOR

Replace JSON-based bundle manifest with a CBOR-encoded format. The manifest
is now a canonical CBOR map with order-strict key decoding, raw 32-byte hash
payloads (instead of hex-encoded JSON), and compact binary representation.

ext/js/src/manifest.js

@@ -33,7 +33,7 @@ export function validateManifest(manifest) {
       `unsupported node hash algorithm: ${tree.nodeHash.algorithm}`
     );
   }
-  if (tree.nodeHash.domain !== "tricu.merkle.node.v1" && tree.nodeHash.domain !== "arborix.merkle.node.v1") {
+  if (tree.nodeHash.domain !== "arborix.merkle.node.v1") {
     throw new Error(
       `unsupported node hash domain: ${tree.nodeHash.domain}`
     );