feat(commons): extend OpcUaEndpointConfig with auth, subscription tuning, read/filter knobs

Adds POCOs and enums for upcoming OPC UA editor expansion:
- OpcUaUserTokenType (Anonymous | UsernamePassword | X509Certificate)
- OpcUaUserIdentityConfig (TokenType + Username/Password + CertificatePath/Password)
- OpcUaDeadbandType (Absolute | Percent) + OpcUaDeadbandConfig
- OpcUaTimestampsToReturn (Source | Server | Both)

OpcUaEndpointConfig grows three new scalars (DiscardOldest, SubscriptionPriority,
SubscriptionDisplayName) plus optional UserIdentity and Deadband sub-objects.
Defaults preserve current runtime behavior (anonymous, no deadband, DiscardOldest=true).

src/ScadaLink.Commons/Types/DataConnections/OpcUaDeadbandConfig.cs

@@ -0,0 +1,7 @@
+namespace ScadaLink.Commons.Types.DataConnections;
+
+public sealed class OpcUaDeadbandConfig
+{
+    public OpcUaDeadbandType Type { get; set; } = OpcUaDeadbandType.Absolute;
+    public double Value { get; set; } = 0.0;
+}

src/ScadaLink.Commons/Types/DataConnections/OpcUaDeadbandType.cs

@@ -0,0 +1,7 @@
+namespace ScadaLink.Commons.Types.DataConnections;
+
+public enum OpcUaDeadbandType
+{
+    Absolute,
+    Percent
+}

src/ScadaLink.Commons/Types/DataConnections/OpcUaEndpointConfig.cs

@@ -18,6 +18,16 @@ public sealed class OpcUaEndpointConfig
     public int KeepAliveCount { get; set; } = 10;
     public int LifetimeCount { get; set; } = 30;
     public int MaxNotificationsPerPublish { get; set; } = 100;
+    public bool DiscardOldest { get; set; } = true;
+    public byte SubscriptionPriority { get; set; } = 0;
+    public string SubscriptionDisplayName { get; set; } = "ScadaLink";
+
+    // Read / filter
+    public OpcUaTimestampsToReturn TimestampsToReturn { get; set; } = OpcUaTimestampsToReturn.Source;
+    public OpcUaDeadbandConfig? Deadband { get; set; }
+
+    // Authentication (optional; null = anonymous)
+    public OpcUaUserIdentityConfig? UserIdentity { get; set; }
 
     // Heartbeat (optional)
     public OpcUaHeartbeatConfig? Heartbeat { get; set; }

src/ScadaLink.Commons/Types/DataConnections/OpcUaTimestampsToReturn.cs

@@ -0,0 +1,8 @@
+namespace ScadaLink.Commons.Types.DataConnections;
+
+public enum OpcUaTimestampsToReturn
+{
+    Source,
+    Server,
+    Both
+}

src/ScadaLink.Commons/Types/DataConnections/OpcUaUserIdentityConfig.cs

@@ -0,0 +1,10 @@
+namespace ScadaLink.Commons.Types.DataConnections;
+
+public sealed class OpcUaUserIdentityConfig
+{
+    public OpcUaUserTokenType TokenType { get; set; } = OpcUaUserTokenType.Anonymous;
+    public string Username { get; set; } = "";
+    public string Password { get; set; } = "";
+    public string CertificatePath { get; set; } = "";
+    public string CertificatePassword { get; set; } = "";
+}

src/ScadaLink.Commons/Types/DataConnections/OpcUaUserTokenType.cs

@@ -0,0 +1,8 @@
+namespace ScadaLink.Commons.Types.DataConnections;
+
+public enum OpcUaUserTokenType
+{
+    Anonymous,
+    UsernamePassword,
+    X509Certificate
+}