Stabilize amsg-instant SSE/Web Push parity e2e assertion in release workflow

[Copilot]

The release GitHub Actions job was failing due to a flaky e2e assertion in @rei-standard/amsg-instant, not a production runtime defect. The test assumed intercepted Web Push backup calls would always arrive in SSE payload order, which is not guaranteed under async execution.

• Problem focus

  • packages/rei-standard-amsg/instant/test/e2e.test.mjs had an order-sensitive assertion in the SSE parity test (payloads vs decrypted backups).

• Change made

  • Kept the parity check intact, but normalized backup ordering before comparison.
  • Sort decrypted backup payloads by messageIndex so the assertion compares semantic sequence rather than fetch timing.

• Why this is the right scope

  • Test-only, surgical change.
  • Preserves existing contract checks (messageId parity between SSE and Web Push) while removing nondeterministic ordering assumptions.

const backups = [];
for (const call of router.pushCalls) {
  backups.push(JSON.parse(await decryptCapturedPushBody(call.body, subKit)));
}
backups.sort((a, b) => a.messageIndex - b.messageIndex);

assert.equal(backups[0].messageId, payloads[0].messageId);
assert.equal(backups[1].messageId, payloads[1].messageId);