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>

site/plugins/code-editor/eslint.config.mjs

@@ -0,0 +1,28 @@
+import js from "@eslint/js";
+import prettier from "eslint-config-prettier";
+import vue from "eslint-plugin-vue";
+
+export default [
+	js.configs.recommended,
+	...vue.configs["flat/vue2-recommended"],
+	prettier,
+	{
+		rules: {
+			"vue/attributes-order": "error",
+			"vue/component-definition-name-casing": "off",
+			"vue/html-closing-bracket-newline": [
+				"error",
+				{
+					singleline: "never",
+					multiline: "always"
+				}
+			],
+			"vue/multi-word-component-names": "off",
+			"vue/require-default-prop": "off",
+			"vue/require-prop-types": "error"
+		},
+		languageOptions: {
+			ecmaVersion: 2022
+		}
+	}
+];