feat: update homepage template with start/abandon game UI

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

templates/homepage/index.html.twig

@@ -1,9 +1,25 @@
 {% extends 'base.html.twig' %}
 
 {% block body %}
-    <div {{ react_component('GameGrid', {
-        grid: grid,
-        width: width,
-        middle: middle,
-    }) }}></div>
+    {% if game %}
+        <div class="game-actions">
+            <form method="post" action="{{ path('app_game_abandon', {id: game.id}) }}">
+                <input type="hidden" name="_token" value="{{ csrf_token('game_abandon') }}">
+                <button type="submit" class="btn btn-abandon">Abandonner</button>
+            </form>
+        </div>
+
+        <div {{ react_component('GameGrid', {
+            grid: grid,
+            width: width,
+            middle: middle,
+        }) }}></div>
+    {% else %}
+        <div class="game-start-container">
+            <form method="post" action="{{ path('app_game_start') }}">
+                <input type="hidden" name="_token" value="{{ csrf_token('game_start') }}">
+                <button type="submit" class="btn btn-primary btn-start">Commencer une partie</button>
+            </form>
+        </div>
+    {% endif %}
 {% endblock %}