Fix Company Settings save, invoice PAID stamp, and purge script

- Company Settings: switch save button from type=submit to type=button
  to bypass HTML5 form validation blocking the submit event; replace
  AutoMapper Map() with explicit property assignment so EF change
  tracking reliably detects mutations; fix showButtonSuccess() never
  re-enabling the button after a successful save
- Invoice PDF: move PAID stamp into the header row as a centered middle
  column so it sits between the company and invoice blocks without
  adding height to the document
- Purge script: use business-date fields instead of CreatedAt so
  imported records (which all share today's CreatedAt) are correctly
  filtered by actual transaction dates

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

src/PowderCoating.Application/Services/PdfService.cs

@@ -147,6 +147,14 @@ public class PdfService : IPdfService
                         column.Item().Text(companyInfo.PrimaryContactEmail).FontSize(9).FontColor(Colors.Grey.Darken1);
                 });
 
+                if (invoice.Status == InvoiceStatus.Paid)
+                {
+                    row.RelativeItem().AlignCenter().AlignMiddle()
+                        .Border(2).BorderColor(Colors.Green.Darken1)
+                        .PaddingVertical(6).PaddingHorizontal(16)
+                        .Text("PAID").FontSize(20).Bold().FontColor(Colors.Green.Darken1).LetterSpacing(0.15f);
+                }
+
                 row.RelativeItem().AlignRight().Column(column =>
                 {
                     column.Item().Text("INVOICE").FontSize(28).Bold().FontColor(accentColor);
@@ -158,16 +166,6 @@ public class PdfService : IPdfService
                 });
             });
 
-            if (invoice.Status == InvoiceStatus.Paid)
-            {
-                col.Item().PaddingVertical(6).AlignCenter().Column(badge =>
-                {
-                    badge.Item().AlignCenter().Border(2).BorderColor(Colors.Green.Darken1)
-                        .PaddingVertical(4).PaddingHorizontal(24)
-                        .Text("PAID").FontSize(18).Bold().FontColor(Colors.Green.Darken1).LetterSpacing(0.15f);
-                });
-            }
-
             col.Item().PaddingVertical(4).LineHorizontal(1).LineColor(accentColor);
         });
     }