feat(wcf): add ConnectViaAddress (WCF Via) for tunneled historian access + wire into C2 spike

When the historian is reached through a port-forward whose local port differs
from the server's real service port, WCF's server-side AddressFilter rejects the
message (To = tunnel port != server port). ConnectViaAddress lets the channel
connect to the tunnel while addressing the SOAP To the real Host/Port endpoint.
Applied in HistorianWcfClientCredentialsHelper.Configure (the critical event
factories already call it). The C2 spike reads HISTORIAN_WCF_EVENT_VIA.

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii

src/AVEVA.Historian.Client/HistorianClientOptions.cs

@@ -53,6 +53,17 @@ public sealed class HistorianClientOptions
     /// </summary>
     public string? ServerDnsIdentity { get; init; }
 
+    /// <summary>
+    /// Optional WCF "Via" address (e.g. <c>net.tcp://host:42568</c>). When set, the SDK's WCF
+    /// channel factories <b>connect</b> to this address while still addressing the SOAP message
+    /// <c>To</c> the logical endpoint built from <see cref="Host"/>/<see cref="Port"/>. Use this when
+    /// the Historian is reached through a port-forwarding tunnel or proxy whose local port differs
+    /// from the server's real service port: point <see cref="Host"/>/<see cref="Port"/> at the
+    /// server's real endpoint (so the server's WCF AddressFilter matches) and set this to the tunnel
+    /// endpoint. Has no effect on the gRPC transport. Default null (connect == address).
+    /// </summary>
+    public string? ConnectViaAddress { get; init; }
+
     /// <summary>
     /// For <see cref="HistorianTransport.RemoteGrpc"/>: when true the channel uses TLS
     /// (<c>https://</c>); when false it uses plaintext (<c>http://</c>). Matches the stock