Adds the Offerings module and retargets the CI/CD pipeline to Api.SlpSoftware

Implements Unit 2 "Offerings" (backend module, admin CRUD UI with
drag-and-drop reordering, public GET /api/v1/offerings endpoint) and
executes the feature's D-15 CI/CD cutover, switching the deploy
pipeline's build/publish target from SlpModularCms.Api to
SlpModularCms.Api.SlpSoftware.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FWyStNL2ZsjrS7FLd7xvvN

src/SlpModularCms.Modules.Offerings/Services/OfferingsService.cs

@@ -0,0 +1,227 @@
+using Microsoft.Extensions.Logging;
+using SlpModularCms.Modules.Offerings.Data.Entities;
+using SlpModularCms.Modules.Offerings.Models;
+using SlpModularCms.Modules.Offerings.Repositories;
+
+namespace SlpModularCms.Modules.Offerings.Services;
+
+public class OfferingsService(IOfferingRepository repository, ILogger<OfferingsService> logger) : IOfferingsService
+{
+    public async Task<IReadOnlyList<OfferingDto>> GetPublicOfferingsAsync()
+    {
+        var offerings = await repository.GetAllAsync();
+        return offerings.Select(ToPublicDto).ToList();
+    }
+
+    public async Task<IReadOnlyList<OfferingAdminDto>> GetAllForAdminAsync()
+    {
+        var offerings = await repository.GetAllAsync();
+        return offerings.Select(ToAdminDto).ToList();
+    }
+
+    public async Task<OfferingAdminDto> CreateAsync(CreateOfferingRequest request, Guid callerId)
+    {
+        var now = DateTimeOffset.UtcNow;
+        var offering = new Offering
+        {
+            Id = Guid.NewGuid(),
+            Title = request.Title,
+            Description = request.Description,
+            Price = request.Price,
+            PriceNote = request.PriceNote,
+            Features = request.Features,
+            CtaLabel = request.CtaLabel,
+            Featured = request.Featured,
+            DisplayOrder = await repository.GetMaxDisplayOrderAsync() + 1,
+            CreatedAt = now,
+            UpdatedAt = now,
+            LastModifiedByUserId = callerId,
+        };
+
+        // BR-OFF-01 (featured exclusivity) touches two rows in one logical action —
+        // transactional per NFR Design Pattern 1 so a mid-operation failure can never
+        // leave two offerings both featured or the new one unsaved after the old one
+        // was already un-featured.
+        if (request.Featured)
+        {
+            await using var transaction = await repository.BeginTransactionAsync();
+            await UnfeatureCurrentAsync();
+            await repository.AddAsync(offering);
+            await repository.SaveChangesAsync();
+            await transaction.CommitAsync();
+        }
+        else
+        {
+            await repository.AddAsync(offering);
+            await repository.SaveChangesAsync();
+        }
+
+        logger.LogInformation(
+            "Offering {OfferingId} {Action} by user {LastModifiedByUserId}",
+            offering.Id, "Created", callerId);
+
+        return ToAdminDto(offering);
+    }
+
+    public async Task<OfferingAdminDto?> UpdateAsync(Guid id, UpdateOfferingRequest request, Guid callerId)
+    {
+        var offering = await repository.GetByIdAsync(id);
+        if (offering is null)
+            return null;
+
+        offering.Title = request.Title;
+        offering.Description = request.Description;
+        offering.Price = request.Price;
+        offering.PriceNote = request.PriceNote;
+        offering.Features = request.Features;
+        offering.CtaLabel = request.CtaLabel;
+        offering.Featured = request.Featured;
+        offering.UpdatedAt = DateTimeOffset.UtcNow;
+        offering.LastModifiedByUserId = callerId;
+
+        if (request.Featured)
+        {
+            await using var transaction = await repository.BeginTransactionAsync();
+            await UnfeatureCurrentAsync(exceptId: offering.Id);
+            repository.Update(offering);
+            await repository.SaveChangesAsync();
+            await transaction.CommitAsync();
+        }
+        else
+        {
+            repository.Update(offering);
+            await repository.SaveChangesAsync();
+        }
+
+        logger.LogInformation(
+            "Offering {OfferingId} {Action} by user {LastModifiedByUserId}",
+            offering.Id, "Updated", callerId);
+
+        return ToAdminDto(offering);
+    }
+
+    public async Task<bool> DeleteAsync(Guid id, Guid callerId)
+    {
+        var offering = await repository.GetByIdAsync(id);
+        if (offering is null)
+            return false;
+
+        // BR-OFF-02: soft delete is never blocked, including for the last remaining offering.
+        offering.IsDeleted = true;
+        offering.DeletedAt = DateTimeOffset.UtcNow;
+        offering.UpdatedAt = offering.DeletedAt.Value;
+        offering.LastModifiedByUserId = callerId;
+
+        repository.Update(offering);
+        await repository.SaveChangesAsync();
+
+        logger.LogInformation(
+            "Offering {OfferingId} {Action} by user {LastModifiedByUserId}",
+            offering.Id, "Deleted", callerId);
+
+        return true;
+    }
+
+    public async Task ReorderAsync(IReadOnlyList<Guid> orderedIds, Guid callerId)
+    {
+        await using var transaction = await repository.BeginTransactionAsync();
+
+        var now = DateTimeOffset.UtcNow;
+        for (var i = 0; i < orderedIds.Count; i++)
+        {
+            var offering = await repository.GetByIdAsync(orderedIds[i]);
+            if (offering is null)
+                continue;
+
+            offering.DisplayOrder = i;
+            offering.UpdatedAt = now;
+            offering.LastModifiedByUserId = callerId;
+            repository.Update(offering);
+        }
+
+        await repository.SaveChangesAsync();
+        await transaction.CommitAsync();
+
+        logger.LogInformation(
+            "Offerings reordered ({Count} items) by user {LastModifiedByUserId}",
+            orderedIds.Count, callerId);
+    }
+
+    public async Task MoveUpAsync(Guid id, Guid callerId)
+    {
+        var offering = await repository.GetByIdAsync(id);
+        if (offering is null)
+            return;
+
+        var previous = await repository.GetPreviousAsync(offering.DisplayOrder);
+        if (previous is null)
+            return; // BR-OFF-03: already first, no-op
+
+        await using var transaction = await repository.BeginTransactionAsync();
+        SwapDisplayOrder(offering, previous, callerId);
+        await repository.SaveChangesAsync();
+        await transaction.CommitAsync();
+    }
+
+    public async Task MoveDownAsync(Guid id, Guid callerId)
+    {
+        var offering = await repository.GetByIdAsync(id);
+        if (offering is null)
+            return;
+
+        var next = await repository.GetNextAsync(offering.DisplayOrder);
+        if (next is null)
+            return; // BR-OFF-03: already last, no-op
+
+        await using var transaction = await repository.BeginTransactionAsync();
+        SwapDisplayOrder(offering, next, callerId);
+        await repository.SaveChangesAsync();
+        await transaction.CommitAsync();
+    }
+
+    private void SwapDisplayOrder(Offering a, Offering b, Guid callerId)
+    {
+        (a.DisplayOrder, b.DisplayOrder) = (b.DisplayOrder, a.DisplayOrder);
+        var now = DateTimeOffset.UtcNow;
+        a.UpdatedAt = now;
+        b.UpdatedAt = now;
+        a.LastModifiedByUserId = callerId;
+        b.LastModifiedByUserId = callerId;
+        repository.Update(a);
+        repository.Update(b);
+    }
+
+    private async Task UnfeatureCurrentAsync(Guid? exceptId = null)
+    {
+        var current = await repository.GetFeaturedAsync();
+        if (current is null || current.Id == exceptId)
+            return;
+
+        current.Featured = false;
+        current.UpdatedAt = DateTimeOffset.UtcNow;
+        repository.Update(current);
+    }
+
+    private static OfferingDto ToPublicDto(Offering o) => new(
+        o.Id.ToString(),
+        o.Title,
+        o.Description,
+        o.Price,
+        o.PriceNote,
+        o.Features,
+        o.CtaLabel,
+        o.Featured
+    );
+
+    private static OfferingAdminDto ToAdminDto(Offering o) => new(
+        o.Id.ToString(),
+        o.Title,
+        o.Description,
+        o.Price,
+        o.PriceNote,
+        o.Features,
+        o.CtaLabel,
+        o.Featured,
+        o.DisplayOrder
+    );
+}