seal options and context classes (#2633)

Co-authored-by: Roger Barreto <19890735+rogerbarreto@users.noreply.github.com>

Author: SergeyMenshykh

dotnet/src/Microsoft.Agents.AI.Abstractions/AIContextProvider.cs

@@ -124,7 +124,7 @@ public virtual JsonElement Serialize(JsonSerializerOptions? jsonSerializerOption
     /// that will be used. Context providers can use this information to determine what additional context
     /// should be provided for the invocation.
     /// </remarks>
-    public class InvokingContext
+    public sealed class InvokingContext
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="InvokingContext"/> class with the specified request messages.
@@ -153,7 +153,7 @@ public InvokingContext(IEnumerable<ChatMessage> requestMessages)
     /// request messages that were used and the response messages that were generated. It also indicates
     /// whether the invocation succeeded or failed.
     /// </remarks>
-    public class InvokedContext
+    public sealed class InvokedContext
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="InvokedContext"/> class with the specified request messages.

dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgentOptions.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Agents.AI;
 /// identifier, display name, operational instructions, and a descriptive summary. It can be used to store and transfer
 /// agent-related metadata within a chat application.
 /// </remarks>
-public class ChatClientAgentOptions
+public sealed class ChatClientAgentOptions
 {
     /// <summary>
     /// Gets or sets the agent id.