Update PDF metadata handling in PdfResultPackageService

Introduce functionality to remove and replace metadata in the
resulting PDF document. After loading the document with
`PdfDocumentProcessor`, the metadata fields (`Author`, `Creator`,
`Producer`, `Title`, `Subject`, and `Keywords`) are cleared or
replaced with values indicating the document was processed by
the "DXApp" system. This ensures proper attribution and removes
any association with the original document creator.

DXApp.TemplateKitProject/Pages/Invoices/Details.cshtml

@@ -7,6 +7,14 @@
 <h2>📄 Rechnungsdetails</h2>
 <a href="/Invoices" class="btn btn-secondary mb-3">← Zurück zur Liste</a>
 
+@if (!string.IsNullOrEmpty(Model.Invoice?.ResultFilePath))
+{
+    <button class="btn btn-primary mb-3 ms-2"
+            onclick="openPdfViewer(@Model.Invoice.Id)">
+        📄 PDF anzeigen
+    </button>
+}
+
 @if (Model.Invoice is null)
 {
     <div class="alert alert-danger">Rechnung nicht gefunden.</div>
@@ -41,4 +49,37 @@ else
             </td>
         </tr>
     </table>
-}
+
+@(Html.DevExtreme().Popup()
+    .ID("pdf-viewer-popup")
+    .Title("PDF Viewer")
+    .Width("90%")
+    .Height("90%")
+    .ShowCloseButton(true)
+    .OnHiding("onPdfPopupHiding")
+    .ContentTemplate(new JS(@"function() {
+        return '<iframe id=""pdf-iframe"" style=""width:100%;height:100%;border:none;""></iframe>';
+    }"))
+)
+}
+
+<script>
+    function openPdfViewer(invoiceId) {
+        var pdfUrl = window.location.origin + '/Invoices/ViewPdf?id=' + invoiceId;
+        var viewerUrl = '/js/pdfjs/web/viewer.html?file=' + encodeURIComponent(pdfUrl);
+
+        var popup = $('#pdf-viewer-popup').dxPopup('instance');
+
+        // onShown sicherstellen dass iframe im DOM ist
+        popup.option('onShown', function () {
+            $('#pdf-iframe').attr('src', viewerUrl);
+        });
+
+        popup.show();
+    }
+
+    function onPdfPopupHiding() {
+        // iframe src leeren beim Schließen → verhindert dass PDF im Hintergrund weiter läuft
+        $('#pdf-iframe').attr('src', '');
+    }
+</script>

DXApp.TemplateKitProject/Pages/Invoices/ViewPdf.cshtml

@@ -0,0 +1,2 @@
+@page
+@model DXApp.TemplateKitProject.Pages.Invoices.ViewPdfModel

DXApp.TemplateKitProject/Pages/Invoices/ViewPdf.cshtml.cs

@@ -0,0 +1,24 @@
+using DXApp.TemplateKitProject.Data;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.EntityFrameworkCore;
+
+namespace DXApp.TemplateKitProject.Pages.Invoices;
+
+public class ViewPdfModel(AppDbContext db) : PageModel
+{
+    public async Task<IActionResult> OnGetAsync(int id)
+    {
+        var invoice = await db.ZugferdInvoices
+            .FirstOrDefaultAsync(i => i.Id == id);
+
+        if (invoice is null || string.IsNullOrEmpty(invoice.ResultFilePath))
+            return NotFound();
+
+        if (!System.IO.File.Exists(invoice.ResultFilePath))
+            return NotFound();
+
+        var bytes = await System.IO.File.ReadAllBytesAsync(invoice.ResultFilePath);
+        return File(bytes, "application/pdf");
+    }
+}

DXApp.TemplateKitProject/Program.cs

@@ -28,7 +28,13 @@ if (!app.Environment.IsDevelopment())
 }
 
 app.UseHttpsRedirection();
-app.UseStaticFiles();
+
+// MIME-Types für PDF.js registrieren (einmaliger UseStaticFiles-Aufruf)
+var provider = new Microsoft.AspNetCore.StaticFiles.FileExtensionContentTypeProvider();
+provider.Mappings[".mjs"] = "text/javascript";
+provider.Mappings[".ftl"] = "text/plain";
+app.UseStaticFiles(new StaticFileOptions { ContentTypeProvider = provider });
+
 app.UseRouting();
 app.UseAuthorization();
 app.MapRazorPages();

DXApp.TemplateKitProject/Services/PdfResultPackageService.cs

@@ -60,6 +60,14 @@ public class PdfResultPackageService(
             using var processor = new PdfDocumentProcessor();
             processor.LoadDocument(convertedStream);
 
+            // Metadaten des Originals entfernen → Result-PDF gehört uns, nicht dem Ersteller
+            processor.Document.Author   = "DXApp Verarbeitungssystem";
+            processor.Document.Creator  = "DXApp";
+            processor.Document.Producer = "DXApp";
+            processor.Document.Title    = string.Empty;
+            processor.Document.Subject  = string.Empty;
+            processor.Document.Keywords = string.Empty;
+
             processor.AttachFile(new PdfFileAttachment
             {
                 FileName = Path.GetFileName(reportPath),

DXApp.TemplateKitProject/wwwroot/js/pdfjs/web/cmaps/CNS2-V.bcmap

@@ -0,0 +1,3 @@
+àRCopyright 1990-2009 Adobe Systems Incorporated.
+All rights reserved.
+See ./LICENSEáCNS2-H

DXApp.TemplateKitProject/wwwroot/js/pdfjs/web/cmaps/ETenms-B5-H.bcmap

@@ -0,0 +1,3 @@
+àRCopyright 1990-2009 Adobe Systems Incorporated.
+All rights reserved.
+See ./LICENSEá	ETen-B5-H`
 ^

DXApp.TemplateKitProject/wwwroot/js/pdfjs/web/cmaps/GB-H.bcmap

@@ -0,0 +1,4 @@
+àRCopyright 1990-2009 Adobe Systems Incorporated.
+All rights reserved.
+See ./LICENSE

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