fix(cmc): readOffer must use streams not streamIds on events.get

`readOffer` was calling `events.get` with `streamIds: [...]` which
the api-server schema rejects with OBJECT_ADDITIONAL_PROPERTIES.
`events.get` takes `streams` (recursive read filter); `streamIds` is
the `events.create` write target. The four other `events.get` callers
in this file (listInvites, waitForAccept, listAcceptedRelationships)
all already use `streams` correctly.

Reproduces 100% against any open-pryv.io running the CMC plugin —
any `cmc.readOffer(capabilityUrl)` call throws on the first await.

No new tests in this PR — existing cmc.test.js suite mocks the
Connection.apiOne layer and doesn't exercise the wire-shape; the
schema mismatch only surfaces against a real api-server. End-to-end
verification via an HDS-side scenario test runs green post-fix.

Author: perki

components/pryv-cmc/src/index.js

@@ -550,8 +550,12 @@ async function requestScopeUpdate (conn, params) {
 async function readOffer (capabilityUrl, opts) {
   const pryv = (opts && opts.pryv) || require('pryv');
   const cap = new pryv.Connection(capabilityUrl);
+  // `events.get` takes `streams` (recursive read filter), not `streamIds`
+  // (which is the events.create write target). Mirror the field used by
+  // the other events.get callers in this file (listInvites, waitForAccept,
+  // listAcceptedRelationships).
   const events = await cap.apiOne('events.get', {
-    streamIds: [NS_INTERNAL + ':offer'],
+    streams: [NS_INTERNAL + ':offer'],
     limit: 1
   }, 'events');
   if (events.length === 0) {