feat: Implement DefaultCryptoHmac for compliance-aware HMAC operations

- Added DefaultCryptoHmac class implementing ICryptoHmac interface.
- Introduced purpose-based HMAC computation methods.
- Implemented verification methods for HMACs with constant-time comparison.
- Created HmacAlgorithms and HmacPurpose classes for well-known identifiers.
- Added compliance profile support for HMAC algorithms.
- Included asynchronous methods for HMAC computation from streams.

src/__Libraries/StellaOps.Cryptography/HmacAlgorithms.cs

@@ -0,0 +1,55 @@
+namespace StellaOps.Cryptography;
+
+/// <summary>
+/// Well-known HMAC algorithm identifiers used by compliance profiles.
+/// </summary>
+public static class HmacAlgorithms
+{
+    /// <summary>
+    /// HMAC using SHA-256 (FIPS 198-1, RFC 2104).
+    /// Used by: world, fips, kcmvp, eidas profiles.
+    /// </summary>
+    public const string HmacSha256 = "HMAC-SHA256";
+
+    /// <summary>
+    /// HMAC using SHA-384 (FIPS 198-1, RFC 2104).
+    /// </summary>
+    public const string HmacSha384 = "HMAC-SHA384";
+
+    /// <summary>
+    /// HMAC using SHA-512 (FIPS 198-1, RFC 2104).
+    /// </summary>
+    public const string HmacSha512 = "HMAC-SHA512";
+
+    /// <summary>
+    /// HMAC using GOST R 34.11-2012 Stribog 256-bit (RFC 6986).
+    /// Used by: gost profile.
+    /// </summary>
+    public const string HmacGost3411 = "HMAC-GOST3411";
+
+    /// <summary>
+    /// HMAC using SM3 (GB/T 32905-2016).
+    /// Used by: sm profile.
+    /// </summary>
+    public const string HmacSm3 = "HMAC-SM3";
+
+    /// <summary>
+    /// All known HMAC algorithms for validation.
+    /// </summary>
+    public static readonly IReadOnlyList<string> All = new[]
+    {
+        HmacSha256,
+        HmacSha384,
+        HmacSha512,
+        HmacGost3411,
+        HmacSm3
+    };
+
+    /// <summary>
+    /// Validates whether the given algorithm is a known HMAC algorithm.
+    /// </summary>
+    /// <param name="algorithmId">The algorithm identifier to validate.</param>
+    /// <returns>True if the algorithm is known; otherwise, false.</returns>
+    public static bool IsKnown(string? algorithmId)
+        => !string.IsNullOrWhiteSpace(algorithmId) && All.Contains(algorithmId);
+}