feat(workflow): Fixes #39 - Installation linters

Author: RustyRory

app/backend/eslint.config.mjs

@@ -0,0 +1,19 @@
+import globals from "globals";
+import pluginPrettier from "eslint-plugin-prettier";
+import { defineConfig } from "eslint/config";
+
+export default defineConfig([
+  {
+    files: ["**/*.{js,mjs,cjs}"], // tous les fichiers JS côté backend
+    languageOptions: {
+      globals: globals.node, // globals Node
+      parserOptions: { ecmaVersion: 2025, sourceType: "module" },
+    },
+    plugins: {
+      prettier: pluginPrettier,
+    },
+    rules: {
+      "prettier/prettier": "error", // toutes les erreurs de style Prettier seront signalées par ESLint
+    },
+  },
+]);