feat(api): PUT /api/v1/users/{id}/permisos/overrides + excepciones domain + ExceptionFilter [UDT-009]

src/api/SIGCM2.Domain/Exceptions/GrantDenyOverlapException.cs

@@ -0,0 +1,16 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// UDT-009: Thrown when the same code appears in both grant and deny arrays.
+/// Maps to 400 { title: "grant-deny-overlap", overlap: [...] }.
+/// </summary>
+public sealed class GrantDenyOverlapException : Exception
+{
+    public IReadOnlyList<string> Overlap { get; }
+
+    public GrantDenyOverlapException(IReadOnlyList<string> overlap)
+        : base($"Los siguientes códigos aparecen en grant y deny simultáneamente: {string.Join(", ", overlap)}")
+    {
+        Overlap = overlap;
+    }
+}