Add "public" setting to contests

app/views/contests/_form.html.slim

@@ -9,6 +9,11 @@
       .form-floating
         = form.select :lang, Languages::AVAILABLE_LANGUAGES.map { |lang| [ lang[:name], lang[:id] ] }, {}, class: "form-select"
         = form.label :lang
+  .row.mb-3
+    .col
+      .form-check.form-switch
+        = form.check_box :public, class: "form-check-input"
+        = form.label :public
   .row.mb-3
     .col
       .form-check.form-switch

app/views/contests/show.html.slim

@@ -14,8 +14,12 @@ javascript:
 
 .row.mb-5
   .col
-    a.btn.btn-success href="/public/#{@contest.slug}"
-      = t("contests.show.open_public_scoreboard")
+    - if @contest.public
+      a.btn.btn-success href="/public/#{@contest.slug}"
+        = t("contests.show.open_public_scoreboard")
+    - else
+      a.btn.btn-success.disabled
+        = t("contests.show.public_scoreboard_disabled")
     button.btn.btn-success.ms-3 onclick="copyExtensionUrlToClipboard()"
       css:
         button > svg {