chore: upgrade to eslint 9 with flat config

Author: ben-zhang-at-salesforce

eslint.config.js

@@ -0,0 +1,31 @@
+const eslintConfigLwc = require("@salesforce/eslint-config-lwc");
+const graphAnalyzer = require("@salesforce/eslint-plugin-lwc-graph-analyzer");
+
+const globals = require("globals");
+
+module.exports = [
+  {
+    ignores: ["!force-app/main/default/lwc/**"],
+  },
+  ...eslintConfigLwc.configs.recommended,
+  {
+    ...graphAnalyzer.configs.recommended,
+    plugins: {
+      "@salesforce/lwc-graph-analyzer": graphAnalyzer,
+    },
+  },
+  {
+    files: ["**/__tests__/**/*.js"],
+    languageOptions: {
+      globals: {
+        ...globals.node,
+      },
+    },
+  },
+  {
+    // lightning/uiGraphQLApi is required for offline support
+    rules: {
+      "@lwc/lwc/newer-version-available": "off",
+    },
+  },
+];

force-app/main/default/lwc/.eslintrc.json

@@ -1,19 +1,20 @@
 {
     "compilerOptions": {
-        "experimentalDecorators": true
+        "experimentalDecorators": true,
+        "baseUrl": ".",
+        "paths": {
+            "c/*": [
+                "*"
+            ]
+        }
     },
     "include": [
         "**/*",
         "../../../../.sfdx/typings/lwc/**/*.d.ts"
     ],
-    "paths": {
-        "c/*": [
-            "*"
-        ]
-    },
     "typeAcquisition": {
         "include": [
             "jest"
         ]
     }
-}
+}