Add invoice context mapping

Distribution/Data/AppDBContext.cs

@@ -20,6 +20,7 @@ public class AppDBContext(DbContextOptions<AppDBContext> options) : DbContext(op
     public DbSet<Sale> Sales { get; set; }
     public DbSet<Order> Orders { get; set; }
     public DbSet<OrderItem> OrderItems { get; set; }
+    public DbSet<Invoice> Invoices { get; set; }
     public DbSet<DeliveryRun> DeliveryRuns { get; set; }
     public DbSet<User> Users { get; set; }
     public DbSet<Role> Roles { get; set; }
@@ -64,8 +65,11 @@ public class AppDBContext(DbContextOptions<AppDBContext> options) : DbContext(op
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
+        // OrderItem uses its inherited Template.Id as PK (no composite key on
+        // {FK_OrderId, FK_ItemId}) so that editing a PO's items can soft-delete the current
+        // row and insert a fresh one for the same item — versioning per order_invoice_lifecycle.md.
         modelBuilder.Entity<OrderItem>()
-            .HasKey(oi => new { oi.FK_OrderId, oi.FK_ItemId });
+            .HasIndex(oi => oi.FK_OrderId);
 
         modelBuilder.Entity<RolePermission>()
             .HasKey(rp => new { rp.FK_RoleId, rp.FK_PermissionId });
@@ -143,8 +147,54 @@ public class AppDBContext(DbContextOptions<AppDBContext> options) : DbContext(op
             .HasOne(o => o.Sale)
             .WithMany()
             .HasForeignKey(o => o.FK_SaleId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
+        modelBuilder.Entity<Order>()
+            .HasOne(o => o.CreatedByUser)
+            .WithMany()
+            .HasForeignKey(o => o.CreatedByUserId)
             .OnDelete(DeleteBehavior.Restrict);
 
+        modelBuilder.Entity<Order>()
+            .HasOne(o => o.ConfirmedByUser)
+            .WithMany()
+            .HasForeignKey(o => o.ConfirmedByUserId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
+        // Order.InvoiceId is a plain column with no DB-level FK constraint — deliberately
+        // unmapped as a relationship, per order_invoice_lifecycle.md.
+        modelBuilder.Entity<Order>()
+            .Property(o => o.InvoiceId)
+            .HasColumnName("InvoiceId");
+
+        modelBuilder.Entity<Invoice>()
+            .HasOne(i => i.Order)
+            .WithMany()
+            .HasForeignKey(i => i.FK_OrderId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        modelBuilder.Entity<Invoice>()
+            .HasOne(i => i.CreatedByUser)
+            .WithMany()
+            .HasForeignKey(i => i.CreatedByUserId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        modelBuilder.Entity<Invoice>()
+            .HasOne(i => i.PrintedByUser)
+            .WithMany()
+            .HasForeignKey(i => i.PrintedByUserId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
+        modelBuilder.Entity<Invoice>()
+            .HasOne(i => i.FinalizedByUser)
+            .WithMany()
+            .HasForeignKey(i => i.FinalizedByUserId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
         modelBuilder.Entity<SchemeRedemption>()
             .HasOne(r => r.Scheme)
             .WithMany(s => s.Redemptions)