Add post-quantum cryptography support with PqSoftCryptoProvider

- Implemented PqSoftCryptoProvider for software-only post-quantum algorithms (Dilithium3, Falcon512) using BouncyCastle.
- Added PqSoftProviderOptions and PqSoftKeyOptions for configuration.
- Created unit tests for Dilithium3 and Falcon512 signing and verification.
- Introduced EcdsaPolicyCryptoProvider for compliance profiles (FIPS/eIDAS) with explicit allow-lists.
- Added KcmvpHashOnlyProvider for KCMVP baseline compliance.
- Updated project files and dependencies for new libraries and testing frameworks.

src/Cli/StellaOps.Cli/Extensions/CommandLineExtensions.cs

@@ -1,32 +1,44 @@
+using System;
 using System.CommandLine;
-
 namespace StellaOps.Cli.Extensions;
 
 /// <summary>
 /// Compatibility extensions for System.CommandLine 2.0.0-beta5+ API changes.
-/// These restore the older extension method patterns that were used in earlier versions.
-/// See: https://learn.microsoft.com/en-us/dotnet/standard/commandline/migration-guide-2.0.0-beta5
+/// These restore the older helper methods the codebase relied on.
 /// </summary>
 public static class CommandLineExtensions
 {
     /// <summary>
-    /// Sets the default value for an option (compatibility shim for older API).
-    /// In beta5+, this maps to DefaultValueFactory.
+    /// Set a default value for an option.
     /// </summary>
     public static Option<T> SetDefaultValue<T>(this Option<T> option, T defaultValue)
     {
+        ArgumentNullException.ThrowIfNull(option);
         option.DefaultValueFactory = _ => defaultValue;
         return option;
     }
 
     /// <summary>
-    /// Restricts the option to accept only the specified values (compatibility shim).
-    /// Works for both Option&lt;string&gt; and Option&lt;string?&gt;.
+    /// Restrict the option to a fixed set of values and add completions.
     /// </summary>
     public static Option<T> FromAmong<T>(this Option<T> option, params string[] allowedValues)
-        where T : class?
     {
-        option.AcceptOnlyFromAmong(allowedValues);
+        ArgumentNullException.ThrowIfNull(option);
+        if (allowedValues is { Length: > 0 })
+        {
+            option.AcceptOnlyFromAmong(allowedValues);
+        }
+
+        return option;
+    }
+
+    /// <summary>
+    /// Mark the option as required (compatibility shim for the old Required property).
+    /// </summary>
+    public static Option<T> Required<T>(this Option<T> option, bool isRequired = true)
+    {
+        ArgumentNullException.ThrowIfNull(option);
+        option.Required = isRequired;
         return option;
     }
 }