feat(lmxproxy): phase 5 — client core (ILmxProxyClient, connection, read/write/subscribe)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lmxproxy/src/ZB.MOM.WW.LmxProxy.Client/ClientConfiguration.cs

@@ -0,0 +1,13 @@
+namespace ZB.MOM.WW.LmxProxy.Client;
+
+/// <summary>
+/// Configuration options for the LmxProxy client, typically set via the builder.
+/// </summary>
+public class ClientConfiguration
+{
+    /// <summary>Maximum number of retry attempts for transient failures.</summary>
+    public int MaxRetryAttempts { get; set; } = 0;
+
+    /// <summary>Base delay between retries (exponential backoff applied).</summary>
+    public TimeSpan RetryDelay { get; set; } = TimeSpan.FromSeconds(1);
+}