Add Skins as a side game for Bingo Bango Bongo

Players can now opt into a Skins side game when creating a BBB round.
The side game uses the same skins settings (carryover, net/gross, skin
value, double back nine). The scorecard gains a third Skins tab during
play and on the summary; the BBB leaderboard continues to rank by BBB
points.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/templates/games/summary.html

@@ -84,11 +84,12 @@
   {# Scorecard toggle #}
   <div class="scorecard-toggle" style="margin-top:1rem;">
     <button @click="view = 'strokes'" :class="{ active: view === 'strokes' }">Strokes</button>
-    {% if game.format == 'skins' %}
-    <button @click="view = 'skins'" :class="{ active: view === 'skins' }">Skins</button>
-    {% else %}
+    {% if game.format != 'skins' %}
     <button @click="view = 'points'" :class="{ active: view === 'points' }">Points</button>
     {% endif %}
+    {% if game.format == 'skins' or side_skins_enabled %}
+    <button @click="view = 'skins'" :class="{ active: view === 'skins' }">Skins</button>
+    {% endif %}
   </div>
 
   {# Strokes scorecard #}
@@ -204,7 +205,7 @@
   </table>
 
   {# Skins scorecard #}
-  {% if game.format == 'skins' %}
+  {% if game.format == 'skins' or side_skins_enabled %}
   <table class="scorecard" x-show="view === 'skins'">
     <thead>
       <tr>