Enable tagged PDF export for html2pdf renders

Chrome PrintToPDF now requests a structure tree and document
outline by default, with optional RenderConfig overrides. Add
lang="en" on the e-signature certificate template so /Lang is
emitted.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/html2pdf/converter_test.go

@@ -72,6 +72,26 @@ func TestWithLogger(t *testing.T) {
 	assert.NotNil(t, converter.l)
 }
 
+func TestGenerateTaggedPDFEnabled(t *testing.T) {
+	assert.True(t, generateTaggedPDFEnabled(RenderConfig{}))
+
+	disabled := false
+	assert.False(t, generateTaggedPDFEnabled(RenderConfig{GenerateTaggedPDF: &disabled}))
+
+	enabled := true
+	assert.True(t, generateTaggedPDFEnabled(RenderConfig{GenerateTaggedPDF: &enabled}))
+}
+
+func TestGenerateDocumentOutlineEnabled(t *testing.T) {
+	assert.True(t, generateDocumentOutlineEnabled(RenderConfig{}))
+
+	disabled := false
+	assert.False(t, generateDocumentOutlineEnabled(RenderConfig{GenerateDocumentOutline: &disabled}))
+
+	enabled := true
+	assert.True(t, generateDocumentOutlineEnabled(RenderConfig{GenerateDocumentOutline: &enabled}))
+}
+
 func TestGetPageDimensions(t *testing.T) {
 	tests := []struct {
 		name        string
@@ -212,6 +232,7 @@ func TestGeneratePDF_WithValidChrome(t *testing.T) {
 
 	// Verify it looks like a PDF file (starts with PDF magic bytes)
 	assert.True(t, bytes.HasPrefix(pdfContent, []byte("%PDF-")))
+	assert.Contains(t, string(pdfContent), "/StructTreeRoot")
 }
 
 func TestGeneratePDF_ScaleHandling(t *testing.T) {