feat: add suitelink client runtime and test harness

tests/SuiteLink.Client.Tests/Protocol/SuiteLinkHandshakeCodecTests.cs

@@ -1,5 +1,6 @@
 using System.Buffers.Binary;
 using SuiteLink.Client.Protocol;
+using SuiteLink.Client.Tests.Fixtures;
 
 namespace SuiteLink.Client.Tests.Protocol;
 
@@ -33,9 +34,7 @@ public sealed class SuiteLinkHandshakeCodecTests
     [Fact]
     public void ParseNormalHandshakeAck_WithNormalAckFrame_ReturnsAckData()
     {
-        // Fixed vector for normal ACK assumption:
-        // remaining=0x0006, type=0x0001, payload=0xA1B2C3, marker=0xA5.
-        byte[] frame = [0x06, 0x00, 0x01, 0x00, 0xA1, 0xB2, 0xC3, 0xA5];
+        var frame = FixtureBytes.Read("handshake-ack-normal.bin");
 
         var ack = SuiteLinkHandshakeCodec.ParseNormalHandshakeAck(frame);