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.Cli/Services/Models/RuntimePolicyEvaluationModels.cs

@@ -17,9 +17,9 @@ internal sealed record RuntimePolicyEvaluationResult(
 internal sealed record RuntimePolicyImageDecision(
     string PolicyVerdict,
     bool? Signed,
-    bool? HasSbom,
+    bool? HasSbomReferrers,
     IReadOnlyList<string> Reasons,
     RuntimePolicyRekorReference? Rekor,
     IReadOnlyDictionary<string, object?> AdditionalProperties);
 
-internal sealed record RuntimePolicyRekorReference(string? Uuid, string? Url);
+internal sealed record RuntimePolicyRekorReference(string? Uuid, string? Url, bool? Verified);

src/StellaOps.Cli/Services/Models/Transport/RuntimePolicyEvaluationTransport.cs

@@ -42,8 +42,12 @@ internal sealed class RuntimePolicyEvaluationImageDocument
     [JsonPropertyName("signed")]
     public bool? Signed { get; set; }
 
+    [JsonPropertyName("hasSbomReferrers")]
+    public bool? HasSbomReferrers { get; set; }
+
+    // Legacy field kept for pre-contract-sync services.
     [JsonPropertyName("hasSbom")]
-    public bool? HasSbom { get; set; }
+    public bool? HasSbomLegacy { get; set; }
 
     [JsonPropertyName("reasons")]
     public List<string>? Reasons { get; set; }
@@ -62,4 +66,7 @@ internal sealed class RuntimePolicyRekorDocument
 
     [JsonPropertyName("url")]
     public string? Url { get; set; }
+
+    [JsonPropertyName("verified")]
+    public bool? Verified { get; set; }
 }