stabilizaiton work - projects rework for maintenanceability and ui livening

src/__Libraries/StellaOps.Provcache/Export/BundleSignature.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json.Serialization;
+
+namespace StellaOps.Provcache;
+
+/// <summary>
+/// DSSE signature envelope for bundle integrity.
+/// </summary>
+public sealed record BundleSignature
+{
+    /// <summary>
+    /// Signature algorithm (e.g., "ES256", "RS256", "Ed25519").
+    /// </summary>
+    [JsonPropertyName("algorithm")]
+    public required string Algorithm { get; init; }
+
+    /// <summary>
+    /// Key identifier used for signing.
+    /// </summary>
+    [JsonPropertyName("keyId")]
+    public required string KeyId { get; init; }
+
+    /// <summary>
+    /// Base64-encoded signature bytes.
+    /// </summary>
+    [JsonPropertyName("signature")]
+    public required string SignatureBytes { get; init; }
+
+    /// <summary>
+    /// UTC timestamp when bundle was signed.
+    /// </summary>
+    [JsonPropertyName("signedAt")]
+    public required DateTimeOffset SignedAt { get; init; }
+
+    /// <summary>
+    /// Optional certificate chain for verification.
+    /// </summary>
+    [JsonPropertyName("certificateChain")]
+    public IReadOnlyList<string>? CertificateChain { get; init; }
+}