Add channel test providers for Email, Slack, Teams, and Webhook

- Implemented EmailChannelTestProvider to generate email preview payloads.
- Implemented SlackChannelTestProvider to create Slack message previews.
- Implemented TeamsChannelTestProvider for generating Teams Adaptive Card previews.
- Implemented WebhookChannelTestProvider to create webhook payloads.
- Added INotifyChannelTestProvider interface for channel-specific preview generation.
- Created ChannelTestPreviewContracts for request and response models.
- Developed NotifyChannelTestService to handle test send requests and generate previews.
- Added rate limit policies for test sends and delivery history.
- Implemented unit tests for service registration and binding.
- Updated project files to include necessary dependencies and configurations.

src/StellaOps.Concelier.Exporter.Json/JsonFeedExporter.cs

@@ -1,12 +1,16 @@
 using System;
 using System.Globalization;
-using System.IO;
-using System.Linq;
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
-using StellaOps.Concelier.Storage.Mongo.Advisories;
-using StellaOps.Concelier.Storage.Mongo.Exporting;
-using StellaOps.Plugin;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.IO;
+using System.Linq;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Concelier.Core.Events;
+using StellaOps.Concelier.Models;
+using StellaOps.Concelier.Storage.Mongo.Advisories;
+using StellaOps.Concelier.Storage.Mongo.Exporting;
+using StellaOps.Plugin;
 
 namespace StellaOps.Concelier.Exporter.Json;
 
@@ -16,29 +20,32 @@ public sealed class JsonFeedExporter : IFeedExporter
     public const string ExporterId = "export:json";
 
     private readonly IAdvisoryStore _advisoryStore;
-    private readonly JsonExportOptions _options;
-    private readonly IJsonExportPathResolver _pathResolver;
-    private readonly ExportStateManager _stateManager;
-    private readonly ILogger<JsonFeedExporter> _logger;
-    private readonly TimeProvider _timeProvider;
-    private readonly string _exporterVersion;
-
-    public JsonFeedExporter(
-        IAdvisoryStore advisoryStore,
-        IOptions<JsonExportOptions> options,
-        IJsonExportPathResolver pathResolver,
-        ExportStateManager stateManager,
-        ILogger<JsonFeedExporter> logger,
-        TimeProvider? timeProvider = null)
-    {
-        _advisoryStore = advisoryStore ?? throw new ArgumentNullException(nameof(advisoryStore));
-        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
-        _pathResolver = pathResolver ?? throw new ArgumentNullException(nameof(pathResolver));
-        _stateManager = stateManager ?? throw new ArgumentNullException(nameof(stateManager));
-        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-        _timeProvider = timeProvider ?? TimeProvider.System;
-        _exporterVersion = ExporterVersion.GetVersion(typeof(JsonFeedExporter));
-    }
+    private readonly JsonExportOptions _options;
+    private readonly IJsonExportPathResolver _pathResolver;
+    private readonly ExportStateManager _stateManager;
+    private readonly ILogger<JsonFeedExporter> _logger;
+    private readonly TimeProvider _timeProvider;
+    private readonly string _exporterVersion;
+    private readonly IAdvisoryEventLog _eventLog;
+
+    public JsonFeedExporter(
+        IAdvisoryStore advisoryStore,
+        IOptions<JsonExportOptions> options,
+        IJsonExportPathResolver pathResolver,
+        ExportStateManager stateManager,
+        IAdvisoryEventLog eventLog,
+        ILogger<JsonFeedExporter> logger,
+        TimeProvider? timeProvider = null)
+    {
+        _advisoryStore = advisoryStore ?? throw new ArgumentNullException(nameof(advisoryStore));
+        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
+        _pathResolver = pathResolver ?? throw new ArgumentNullException(nameof(pathResolver));
+        _stateManager = stateManager ?? throw new ArgumentNullException(nameof(stateManager));
+        _eventLog = eventLog ?? throw new ArgumentNullException(nameof(eventLog));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _timeProvider = timeProvider ?? TimeProvider.System;
+        _exporterVersion = ExporterVersion.GetVersion(typeof(JsonFeedExporter));
+    }
 
     public string Name => ExporterName;
 
@@ -52,11 +59,12 @@ public sealed class JsonFeedExporter : IFeedExporter
 
         var existingState = await _stateManager.GetAsync(ExporterId, cancellationToken).ConfigureAwait(false);
 
-        var builder = new JsonExportSnapshotBuilder(_options, _pathResolver);
-        var advisoryStream = _advisoryStore.StreamAsync(cancellationToken);
-        var result = await builder.WriteAsync(advisoryStream, exportedAt, exportId, cancellationToken).ConfigureAwait(false);
-
-        var digest = ExportDigestCalculator.ComputeTreeDigest(result);
+        var builder = new JsonExportSnapshotBuilder(_options, _pathResolver);
+        var canonicalAdvisories = await MaterializeCanonicalAdvisoriesAsync(cancellationToken).ConfigureAwait(false);
+        var result = await builder.WriteAsync(canonicalAdvisories, exportedAt, exportId, cancellationToken).ConfigureAwait(false);
+        result = await JsonMirrorBundleWriter.WriteAsync(result, _options, services, _timeProvider, _logger, cancellationToken).ConfigureAwait(false);
+
+        var digest = ExportDigestCalculator.ComputeTreeDigest(result);
         _logger.LogInformation(
             "JSON export {ExportId} wrote {FileCount} files ({Bytes} bytes) covering {AdvisoryCount} advisories with digest {Digest}",
             exportId,
@@ -106,7 +114,34 @@ public sealed class JsonFeedExporter : IFeedExporter
         {
             TryUpdateLatestSymlink(exportRoot, result.ExportDirectory);
         }
-    }
+    }
+
+    private async Task<IReadOnlyList<Advisory>> MaterializeCanonicalAdvisoriesAsync(CancellationToken cancellationToken)
+    {
+        var keys = new SortedSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        await foreach (var advisory in _advisoryStore.StreamAsync(cancellationToken))
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            if (!string.IsNullOrWhiteSpace(advisory.AdvisoryKey))
+            {
+                keys.Add(advisory.AdvisoryKey.Trim());
+            }
+        }
+
+        var advisories = new List<Advisory>(keys.Count);
+        foreach (var key in keys)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            var replay = await _eventLog.ReplayAsync(key, asOf: null, cancellationToken).ConfigureAwait(false);
+            if (!replay.Statements.IsDefaultOrEmpty)
+            {
+                advisories.Add(replay.Statements[0].Advisory);
+            }
+        }
+
+        return advisories;
+    }
 
     private void TryUpdateLatestSymlink(string exportRoot, string exportDirectory)
     {