Integrate shared scoreboard links in contests

app/views/contests/index.html.slim

@@ -2,6 +2,8 @@
   .col
     h4.mb-3
       = t("contests.index.manage_contests")
+      a.ms-3.btn.btn-primary href="/events"
+        = t("events.show.back_to_events")
       .float-end
         a.btn.btn-primary.mb-4 href=new_contest_path
           = t("contests.index.new_contest")
@@ -9,7 +11,7 @@
 .alert.alert-primary role="alert"
   = t("contests.index.message")
 
-.row.row-cols-1.row-cols-md-3.g-4
+.mt-3.row.row-cols-1.row-cols-md-3.g-4
   - @contests.each do |contest|
     .col
       css: