Feat: page Play — backgroundColor, playLink, play-icon + fix slug jouer

- Renommage dossier content 3_play → 3_jouer (slug /jouer)
- Champ backgroundColor (code-editor) dans game.yml + exposé en API
- playLinks simplifié en champ url simple → playLink dans l'API
- Variable CSS --background-color sur la section .play
- Bouton "Jouer" avec icône play-icon (SVG data URI dans buttons.css)
- Plugin sylvainjule/code-editor ajouté via composer

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

src/views/Play.svelte

@@ -61,7 +61,11 @@
   })
 </script>
 
-<section class="play golden-grid slide" aria-label="Jouer">
+<section
+  class="play golden-grid slide"
+  aria-label="Jouer"
+  style={displayedGame?.backgroundColor ? `--background-color: ${displayedGame.backgroundColor}` : ''}
+>
 
   <!-- Fond : image + overlay, crossfade au changement de jeu -->
   <div class="play-bg" class:is-out={isOut} aria-hidden="true">
@@ -144,15 +148,13 @@
       {/if}
 
       <div class="play-actions">
-        {#if displayedGame.playLinks?.length}
-          {#each displayedGame.playLinks as link}
-            <a
-              href={link.url}
-              target="_blank"
-              rel="noopener noreferrer"
-              class="button"
-            >{link.label}</a>
-          {/each}
+        {#if displayedGame.playLink}
+          <a
+            href={displayedGame.playLink}
+            target="_blank"
+            rel="noopener noreferrer"
+            class="button play-icon"
+          >Jouer</a>
         {:else}
           <button class="button" disabled>Coming soon</button>
         {/if}
@@ -184,7 +186,7 @@
 
 <style>
   .play {
-    background: #000;
+    background: var(--background-color);
   }
 
   /* --- Background --- */