Bump ESLint from unsported version to version 9

webapp/eslint.config.mjs

@@ -0,0 +1,78 @@
+import js from "@eslint/js";
+import vue from "eslint-plugin-vue";
+import vueParser from "vue-eslint-parser";
+import babelParser from "@babel/eslint-parser";
+import prettier from "eslint-config-prettier";
+import globals from "globals";
+
+const isProd = process.env.NODE_ENV === "production";
+
+export default [
+  {
+    languageOptions: {
+      globals: {
+        ...globals.node,
+      },
+    },
+  },
+  js.configs.recommended,
+
+  ...vue.configs["flat/recommended"],
+
+  prettier,
+
+  {
+    files: ["**/*.vue", "**/*.js"],
+    languageOptions: {
+      parser: vueParser,
+      parserOptions: {
+        parser: babelParser,
+        requireConfigFile: false,
+        ecmaVersion: 2021,
+        sourceType: "module",
+      },
+      ecmaVersion: 2021,
+      sourceType: "module",
+      globals: {
+        process: "readonly",
+      },
+    },
+
+    plugins: {
+      vue,
+    },
+
+    rules: {
+      // Environment-based rules
+      "no-console": isProd ? "warn" : "off",
+      "no-debugger": isProd ? "warn" : "off",
+
+      // Vue deprecations
+      "vue/no-deprecated-slot-attribute": "warn",
+      "vue/no-deprecated-v-on-native-modifier": "warn",
+      "vue/no-deprecated-dollar-listeners-api": "warn",
+      "vue/no-deprecated-destroyed-lifecycle": "warn",
+      "vue/no-deprecated-dollar-scopedslots-api": "warn",
+      "vue/no-deprecated-events-api": "warn",
+      "vue/no-deprecated-filter": "warn",
+      "vue/no-deprecated-functional-template": "warn",
+      "vue/no-deprecated-html-element-is": "warn",
+      "vue/no-deprecated-inline-template": "warn",
+      "vue/no-deprecated-props-default-this": "warn",
+      "vue/no-deprecated-scope-attribute": "warn",
+      "vue/no-deprecated-v-bind-sync": "warn",
+      "vue/no-deprecated-v-is": "warn",
+      "vue/no-lifecycle-after-await": "warn",
+      "vue/no-watch-after-await": "warn",
+
+      // Vue best practices
+      "vue/require-explicit-emits": "warn",
+      "vue/multi-word-component-names": "warn",
+      "vue/no-v-for-template-key-on-child": "error",
+      "vue/no-v-model-argument": "off",
+
+      "vue/no-unused-components": "warn",
+      "vue/no-unused-vars": "warn",
+    },
+  },
+];