Restructure solution layout by module

src/Aoc/__Libraries/StellaOps.Aoc/AocGuardException.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Immutable;
+
+namespace StellaOps.Aoc;
+
+public sealed class AocGuardException : Exception
+{
+    public AocGuardException(AocGuardResult result)
+        : base("AOC guard validation failed.")
+    {
+        Result = result ?? throw new ArgumentNullException(nameof(result));
+    }
+
+    public AocGuardResult Result { get; }
+
+    public ImmutableArray<AocViolation> Violations => Result.Violations;
+}