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>

vendor/composer/installed.php

@@ -1,9 +1,9 @@
 <?php return array(
     'root' => array(
         'name' => 'getkirby/plainkit',
-        'pretty_version' => '5.2.2',
-        'version' => '5.2.2.0',
-        'reference' => null,
+        'pretty_version' => 'dev-main',
+        'version' => 'dev-main',
+        'reference' => '3cafcf3167251bbbfd64183de5da67c4a488fa7d',
         'type' => 'project',
         'install_path' => __DIR__ . '/../../',
         'aliases' => array(),
@@ -65,9 +65,9 @@
             'dev_requirement' => false,
         ),
         'getkirby/plainkit' => array(
-            'pretty_version' => '5.2.2',
-            'version' => '5.2.2.0',
-            'reference' => null,
+            'pretty_version' => 'dev-main',
+            'version' => 'dev-main',
+            'reference' => '3cafcf3167251bbbfd64183de5da67c4a488fa7d',
             'type' => 'project',
             'install_path' => __DIR__ . '/../../',
             'aliases' => array(),
@@ -124,6 +124,15 @@
             'aliases' => array(),
             'dev_requirement' => false,
         ),
+        'sylvainjule/code-editor' => array(
+            'pretty_version' => '1.1.0',
+            'version' => '1.1.0.0',
+            'reference' => 'adbc2c8a728994cc57ea72a7f8628f27d202b8df',
+            'type' => 'kirby-plugin',
+            'install_path' => __DIR__ . '/../../site/plugins/code-editor',
+            'aliases' => array(),
+            'dev_requirement' => false,
+        ),
         'symfony/deprecation-contracts' => array(
             'pretty_version' => 'v3.6.0',
             'version' => '3.6.0.0',