fix(abcip): harden Ab.Transport CIP codec and EncapsulationClient (#564, #565)

CIP codec (#564): PatchU16 bounds guard; CipReply content equality; CipPath
port/length/ASCII/odd/oversize validation with ArgumentException for malformed
tag names and routes; CipPath.MessageRouter/ConnectionManager are now
ReadOnlySpan<byte>; refused Forward Open surfaces ForwardOpenRefusedException
with structured general/extended status; test CaptureFile uses BinaryPrimitives.

EncapsulationClient (#565): frame write bounded by the exchange timeout, which
faults (never cancels) the connection; finite positive timeouts enforced at
every entry point; gate wait bounded by the timeout; deterministic reorder of
the 300 ms test; new dispose-during-drain, gate-wait and RegisterSession
zero-context tests.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Tests/Captures/CaptureFile.cs

@@ -1,3 +1,4 @@
+using System.Buffers.Binary;
 namespace ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Tests.Captures;
 
 /// <summary>One EtherNet/IP encapsulation frame from a golden capture.</summary>
@@ -30,15 +31,15 @@ internal static class CaptureFile
     public static byte[] CipPayload(CapturedFrame f)
     {
         var b = f.Bytes;
-        var cmd = BitConverter.ToUInt16(b, 0);          // test-only; fixtures are LE on a LE host
+        var cmd = BinaryPrimitives.ReadUInt16LittleEndian(b.AsSpan(0));         
         if (cmd is not (0x6F or 0x70)) return [];       // only SendRRData / SendUnitData carry CPF items
         var pos = 24 + 4 + 2;                           // header + interface handle + timeout
-        var itemCount = BitConverter.ToUInt16(b, pos); pos += 2;
+        var itemCount = BinaryPrimitives.ReadUInt16LittleEndian(b.AsSpan(pos)); pos += 2;
         byte[] last = [];
         for (var i = 0; i < itemCount; i++)
         {
-            var type = BitConverter.ToUInt16(b, pos);
-            var len = BitConverter.ToUInt16(b, pos + 2);
+            var type = BinaryPrimitives.ReadUInt16LittleEndian(b.AsSpan(pos));
+            var len = BinaryPrimitives.ReadUInt16LittleEndian(b.AsSpan(pos + 2));
             last = b.AsSpan(pos + 4, len).ToArray();
             if (type == 0x00B1) last = last[2..];       // strip connected sequence count
             pos += 4 + len;