Add Project Name field to invoice create and edit forms

Stores ProjectName on the Invoice entity (previously only inherited from the
linked job at display time). Pre-fills from the job when creating from a job.
Migration: AddInvoiceProjectName.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Application/DTOs/Invoice/InvoiceDtos.cs

@@ -89,6 +89,7 @@ public class CreateInvoiceDto
     public string? InternalNotes { get; set; }
     public string? Terms { get; set; }
     public string? CustomerPO { get; set; }
+    public string? ProjectName { get; set; }
     /// <summary>Early-payment discount percentage parsed from the customer's payment terms (e.g., 2.0 for "2/10 Net 30"). Informational — does not auto-apply.</summary>
     public decimal EarlyPaymentDiscountPercent { get; set; }
     /// <summary>Number of days within which the early-payment discount applies (e.g., 10 for "2/10 Net 30").</summary>
@@ -106,6 +107,7 @@ public class UpdateInvoiceDto
     public string? InternalNotes { get; set; }
     public string? Terms { get; set; }
     public string? CustomerPO { get; set; }
+    public string? ProjectName { get; set; }
     public List<CreateInvoiceItemDto> InvoiceItems { get; set; } = new();
 }
 

src/PowderCoating.Application/Mappings/InvoiceProfile.cs

@@ -19,7 +19,7 @@ public class InvoiceProfile : Profile
 
         CreateMap<Invoice, InvoiceDto>()
             .ForMember(d => d.JobNumber, o => o.MapFrom(s => s.Job != null ? s.Job.JobNumber : string.Empty))
-            .ForMember(d => d.ProjectName, o => o.MapFrom(s => s.Job != null ? s.Job.ProjectName : null))
+            .ForMember(d => d.ProjectName, o => o.MapFrom(s => s.ProjectName ?? (s.Job != null ? s.Job.ProjectName : null)))
             .ForMember(d => d.CustomerName, o => o.MapFrom(s => s.Customer != null
                 ? (s.Customer.IsCommercial
                     ? s.Customer.CompanyName