stabilizaiton work - projects rework for maintenanceability and ui livening

src/__Libraries/StellaOps.Provcache.Api/SignerCertificateDto.cs

@@ -0,0 +1,22 @@
+namespace StellaOps.Provcache.Api;
+
+/// <summary>
+/// Signer certificate information in API response.
+/// </summary>
+public sealed class SignerCertificateDto
+{
+    /// <summary>
+    /// Subject of the certificate (e.g., CN=...).
+    /// </summary>
+    public string? Subject { get; init; }
+
+    /// <summary>
+    /// Certificate issuer.
+    /// </summary>
+    public string? Issuer { get; init; }
+
+    /// <summary>
+    /// When the certificate expires.
+    /// </summary>
+    public DateTimeOffset? ExpiresAt { get; init; }
+}