feat: add HTTP and MCP service

src/WxAgent.Service/EventPump.cs

@@ -0,0 +1,30 @@
+using Microsoft.Extensions.Hosting;
+
+namespace WxAgent.Service;
+
+public interface IAgentEventSource
+{
+    IAsyncEnumerable<AgentEvent> ListenAsync(CancellationToken cancellationToken);
+}
+
+public sealed class EventPump(IAgentBackend backend, EventHub hub, ServiceOptions options) : BackgroundService
+{
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        if (backend is not IAgentEventSource source || backend.Capabilities.All(c => c.Operation != "listener-events" || !c.Enabled)) return;
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                await foreach (var item in source.ListenAsync(stoppingToken))
+                {
+                    foreach (var credential in options.ReadCredentials())
+                        if (credential.AccountIds.Length == 0 || credential.AccountIds.Contains(item.AccountId, StringComparer.Ordinal))
+                            hub.Publish(credential.PrincipalId, item);
+                }
+            }
+            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested) { return; }
+            catch (Exception) { await Task.Delay(TimeSpan.FromSeconds(2), stoppingToken); }
+        }
+    }
+}