fix(provider): add a varint 0 for http to match go-libipni

Author: hannahhoward

provider.js

@@ -43,7 +43,7 @@ export class Provider {
    * @param {'bitswap' | 'http' | 'graphsync'} config.protocol - transfer protocol available
    * @param {GraphsyncMetadata} [config.metadata]
    */
-  constructor ({ peerId, addresses, protocol, metadata }) {
+  constructor({ peerId, addresses, protocol, metadata }) {
     if (!protocol || !addresses || !peerId) {
       throw new Error('protocol, addresses, and peerId are required')
     }
@@ -63,8 +63,8 @@ export class Provider {
   * @param {'bitswap' | 'http' | 'graphsync'} protocol
   * @param {GraphsyncMetadata} [metadata] - required if protocol is `graphsync`
   */
-  encodeMetadata (protocol = this.protocol, metadata = this.metadata) {
-    if (protocol === 'http') return HTTP_PREFIX
+  encodeMetadata(protocol = this.protocol, metadata = this.metadata) {
+    if (protocol === 'http') return concat([HTTP_PREFIX, new Uint8Array(varint.encode(0))])
     if (protocol === 'bitswap') return BITSWAP_PREFIX
     if (protocol === 'graphsync') {
       if (!metadata) throw new Error('metadata is required')
@@ -85,7 +85,7 @@ export class Provider {
    * spec: https://github.com/ipni/specs/blob/main/IPNI.md#extendedprovider
    * @param {import('./advertisement').Advertisement} ad
    **/
-  signableBytes (ad) {
+  signableBytes(ad) {
     const text = new TextEncoder()
     const providerOverride = ad.override ? 1 : 0
     return concat([