refactor+feat(backend): ChargeableCharConfig por ProductType + Reactivate + Delete endpoints (PRC-001)

Part A — MedioId → ProductTypeId rename across all C# layers:
  Domain, Application, Infrastructure, API, all test projects.
  Solution was non-compilable after BD refactor (5c1675e); now compiles clean (0 errors).

Part B — PATCH /api/v1/admin/chargeable-chars/{id}/reactivate:
  ReactivateChargeableCharConfigCommand/Handler, SP guard maps 50410/50411/50412
  → ChargeableCharConfigReactivationNotAllowedException(Reason) → HTTP 409.

Part C — DELETE /api/v1/admin/chargeable-chars/{id}:
  DeleteChargeableCharConfigCommand/Handler, physical DELETE on SYSTEM_VERSIONED table.
  KeyNotFoundException → 404 via ExceptionFilter.

Tests: +30 unit tests (TDD RED→GREEN). All 1266 unit tests pass.

tests/SIGCM2.Application.Tests/Pricing/ChargeableChars/DeleteChargeableCharConfigHandlerTests.cs

@@ -0,0 +1,113 @@
+using FluentAssertions;
+using Microsoft.Extensions.Time.Testing;
+using NSubstitute;
+using NSubstitute.ExceptionExtensions;
+using SIGCM2.Application.Abstractions.Persistence;
+using SIGCM2.Application.Audit;
+using SIGCM2.Application.Pricing.ChargeableChars.Delete;
+using SIGCM2.Domain.Pricing.ChargeableChars;
+
+namespace SIGCM2.Application.Tests.Pricing.ChargeableChars;
+
+/// <summary>
+/// PRC-001 — DeleteChargeableCharConfigCommandHandler tests.
+/// Strict TDD — RED written before implementation.
+/// Covers: happy path, not-found, audit emission, audit fail-closed.
+/// </summary>
+public class DeleteChargeableCharConfigHandlerTests
+{
+    private readonly FakeTimeProvider _time = new(new DateTimeOffset(2026, 4, 20, 12, 0, 0, TimeSpan.Zero));
+    private readonly IChargeableCharConfigRepository _repo = Substitute.For<IChargeableCharConfigRepository>();
+    private readonly IAuditLogger _audit = Substitute.For<IAuditLogger>();
+    private readonly DeleteChargeableCharConfigCommandHandler _handler;
+
+    private static ChargeableCharConfig SomeConfig() =>
+        ChargeableCharConfig.Rehydrate(
+            id: 1L, productTypeId: null, symbol: "$", category: ChargeableCharCategories.Currency,
+            price: 1.5m, validFrom: new DateOnly(2026, 1, 1), validTo: null, isActive: true);
+
+    public DeleteChargeableCharConfigHandlerTests()
+    {
+        _repo.GetByIdAsync(1L, Arg.Any<CancellationToken>())
+            .Returns(SomeConfig());
+
+        _handler = new DeleteChargeableCharConfigCommandHandler(_repo, _audit, _time);
+    }
+
+    private static DeleteChargeableCharConfigCommand ValidCmd() => new(Id: 1L);
+
+    // ── Happy path ──────────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task Handle_HappyPath_ReturnsResponse()
+    {
+        var result = await _handler.Handle(ValidCmd());
+
+        result.Should().NotBeNull();
+        result.Id.Should().Be(1L);
+    }
+
+    [Fact]
+    public async Task Handle_HappyPath_CallsDeleteAsync()
+    {
+        await _handler.Handle(ValidCmd());
+
+        await _repo.Received(1).DeleteAsync(1L, Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task Handle_HappyPath_EmitsAuditDelete()
+    {
+        await _handler.Handle(ValidCmd());
+
+        await _audit.Received(1).LogAsync(
+            action: "tasacion.chargeable_char.delete",
+            targetType: "ChargeableCharConfig",
+            targetId: "1",
+            metadata: Arg.Any<object?>(),
+            ct: Arg.Any<CancellationToken>());
+    }
+
+    // ── Not found ───────────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task Handle_ConfigNotFound_ThrowsKeyNotFoundException()
+    {
+        _repo.GetByIdAsync(99L, Arg.Any<CancellationToken>())
+            .Returns((ChargeableCharConfig?)null);
+
+        var act = async () => await _handler.Handle(new DeleteChargeableCharConfigCommand(Id: 99L));
+
+        await act.Should().ThrowAsync<KeyNotFoundException>();
+    }
+
+    // ── Audit fail → rollback (fail-closed) ─────────────────────────────────────
+
+    [Fact]
+    public async Task Handle_AuditThrows_ExceptionPropagates()
+    {
+        _audit.LogAsync(
+                Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>(),
+                Arg.Any<object?>(), Arg.Any<CancellationToken>())
+            .ThrowsAsync(new InvalidOperationException("Audit down"));
+
+        var act = async () => await _handler.Handle(ValidCmd());
+
+        await act.Should().ThrowAsync<InvalidOperationException>()
+            .WithMessage("Audit down");
+    }
+
+    [Fact]
+    public async Task Handle_AuditThrows_DeleteWasCalled_TransactionNotCompleted()
+    {
+        _audit.LogAsync(
+                Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>(),
+                Arg.Any<object?>(), Arg.Any<CancellationToken>())
+            .ThrowsAsync(new InvalidOperationException("Audit down"));
+
+        var act = async () => await _handler.Handle(ValidCmd());
+        await act.Should().ThrowAsync<InvalidOperationException>();
+
+        await _repo.Received(1).DeleteAsync(1L, Arg.Any<CancellationToken>());
+    }
+}