Add contest duration & complete ranking mode implementation

app/views/contests/scoreboard.html.slim

@@ -48,7 +48,7 @@ css:
                     = contestant.completions.where(remaining_pieces: nil).length
                 td style="position: relative"
                   - if index > 0 && contestant.time_seconds > 0 && contestant.completions.where(completed: true).size > 0
-                    .relative-time style="position:absolute; margin: 1px 0 0 100px; font-size: 14px; color: grey"
+                    .relative-time style="position:absolute; margin: 1px 0 0 112px; font-size: 14px; color: grey"
                       |> +
                       = display_time(contestant.time_seconds - @contestants[index - 1].time_seconds)
                   = contestant.display_time

app/views/contests/settings_general_edit.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 :duration, autocomplete: "off", class: "form-control"
+        = form.label :duration, class: "required"
+        .form-text = t("activerecord.attributes.contest.duration_description")
   .row.mb-3
     .col
       .form-floating