Frontend gaps fill work. Testing fixes work. Auditing in progress.

src/Signals/StellaOps.Signals/Scm/Webhooks/IWebhookSignatureValidator.cs

@@ -0,0 +1,16 @@
+namespace StellaOps.Signals.Scm.Webhooks;
+
+/// <summary>
+/// Interface for webhook signature validation.
+/// </summary>
+public interface IWebhookSignatureValidator
+{
+    /// <summary>
+    /// Validates the webhook signature.
+    /// </summary>
+    /// <param name="payload">Raw request body bytes.</param>
+    /// <param name="signature">Signature from request header.</param>
+    /// <param name="secret">Webhook secret.</param>
+    /// <returns>True if signature is valid.</returns>
+    bool IsValid(ReadOnlySpan<byte> payload, string? signature, string secret);
+}