Add PDF generation for QR codes

app/views/contestants/generate_qrcodes.html.slim

@@ -1,20 +1,25 @@
 - if @contest.code.present?
-  .row.mb-4 style="height: calc(100vh - 280px)"
+  .mb-4 style="height: calc(100vh - 280px)"
     .row
       .col
         .alert.alert-info
           = t("contestants.generate_qrcodes.note")
-    .col.d-flex.flex-column style="height: 100%"
-      .d-flex.flex-column style="overflow-y: auto"
+
+    a.mt-3.mb-3.btn.btn-primary href="#{contest_generate_qrcodes_pdf_path(@contest)}.pdf" target="_blank" style="margin-top: -3px"
+      = t("helpers.buttons.download_pdf")
+  
+    .col.d-flex.flex-column style="height: calc(100% - 200px)"
+      .d-flex.flex-column style="overflow-y: auto;"
         - for row in 0..((@contestants.length - 1) / 5)
           .mt-4.d-flex.flex-row
-            - for col in 0..4
-              - if row * 5 + col < @contestants.length
+            - for col in 0..3
+              - if row * 4 + col < @contestants.length
                 .d-flex.flex-column.ms-5 style="align-items: center"
-                  = @contestants[row * 5 + col].name
-                  - if @contestants[row * 5 + col].qrcode.present?
-                    .mt-1 style="width: 180px; height: 180px;"
-                      = @contestants[row * 5 + col].qrcode.html_safe
+                  - if @contestants[row * 4 + col].qrcode.present?
+                    .mt-1 style="width: 128px; height: 120px;"
+                      = @contestants[row * 4 + col].qrcode.html_safe
+                  .name.text-center.mt-3 style="font-size: 0.7rem; max-width: 128px; height: 30px;"
+                    = @contestants[row * 4 + col].name
 - else
   .row
     .col