Add public scoreboard slug & URL

app/views/contests/_form.html.slim

@@ -4,6 +4,12 @@
       .form-floating
         = form.text_field :name, autocomplete: "off", class: "form-control"
         = form.label :name, class: "required"
+  .row.mb-3
+    .col
+      .form-floating
+        = form.text_field :slug, autocomplete: "off", class: "form-control"
+        = form.label :slug, class: "required"
+      .form-text This will be used for building the public scoreboard URL: https://puzzle-scoreboard.org/public/<slug>.
   .row.mb-3
     .col
       .form-check.form-switch

app/views/contests/show.html.slim

@@ -1,4 +1,4 @@
-.row.mb-2
+.row.mb-4
   .col
     css:
       .badges { margin-top: -18px; position: absolute; }
@@ -6,10 +6,16 @@
       - @badges.each do |badge|
         span.badge.text-bg-info.me-2
           = badge
+
+.row.mb-4
+  .col
     .float-end
       a.btn.btn-primary href=edit_contest_path(@contest)
         | Edit contest
-
+    p
+      |> Public scoreboard:
+      = link_to root_url + "public/#{@contest.slug}"
+    
 .row.mb-4
   .col-6
     .row