Restore all zeroed views + add bulk gift certificate creation

The HTML entity sweep script had a bug where it wrote empty files for any
view that contained no target Unicode characters, zeroing out 215 view files.
All views restored from the pre-sweep commit (cefdf3e).

Bulk gift certificate feature:
- BulkCreateGiftCertificateDto with Quantity (1-500), Amount, Reason, Expiry, Notes
- GenerateBulkGiftCertificatePdfAsync on IPdfService / PdfService: one Letter page
  per cert, reusing the same purple/gold branded ComposeGiftCertificateContent helper
- GiftCertificatesController: BulkCreate GET/POST, BulkResult GET, BulkDownloadPdf POST
- Views: BulkCreate.cshtml (form with live total preview), BulkResult.cshtml (table +
  Download All PDF button that POSTs cert IDs to avoid URL length limits)
- gift-certificate-bulk.js: live preview + spinner/disable on submit
- Index.cshtml: Bulk Create button added alongside New Certificate

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

src/PowderCoating.Application/Services/PdfService.cs

@@ -1858,6 +1858,50 @@ public class PdfService : IPdfService
         });
     }
 
+    /// <summary>
+    /// Generates a multi-page PDF containing one gift certificate per page, all using the same
+    /// branded layout as the single-certificate download. Used for bulk print runs (car shows,
+    /// promotions) so staff can hand-cut and distribute a full batch from one print job.
+    /// </summary>
+    public async Task<byte[]> GenerateBulkGiftCertificatePdfAsync(
+        IList<GiftCertificateDto> certs,
+        byte[]? companyLogo,
+        string? companyLogoContentType,
+        CompanyInfoDto companyInfo)
+    {
+        QuestPDF.Settings.License = LicenseType.Community;
+        const string accent = "#7c3aed";
+        const string gold = "#b45309";
+
+        return await Task.Run(() =>
+        {
+            var doc = Document.Create(container =>
+            {
+                foreach (var cert in certs)
+                {
+                    container.Page(page =>
+                    {
+                        page.Size(PageSizes.Letter);
+                        page.Margin(0.75f, Unit.Inch);
+                        page.PageColor(Colors.White);
+                        page.DefaultTextStyle(x => x.FontSize(10).FontFamily("Arial"));
+
+                        page.Content().Element(c => ComposeGiftCertificateContent(c, cert, companyInfo, companyLogo, accent, gold));
+
+                        page.Footer().AlignCenter().Text(text =>
+                        {
+                            text.Span(companyInfo.CompanyName).FontSize(8).FontColor(Colors.Grey.Darken1);
+                            if (!string.IsNullOrWhiteSpace(companyInfo.Phone))
+                                text.Span($"  ·  {FormatPhoneNumber(companyInfo.Phone)}").FontSize(8).FontColor(Colors.Grey.Darken1);
+                        });
+                    });
+                }
+            });
+
+            return doc.GeneratePdf();
+        });
+    }
+
     /// <summary>
     /// Composes the gift certificate body with a decorative double-border frame (outer purple 3pt,
     /// inner gold 1pt) that gives the document a premium printed-certificate appearance. Inside the