Switch to ESLint projectService (#218)

* Switch to ESLint projectService

* Update copilot instructions to remove deleted files

eslint.config.mjs

@@ -9,13 +9,9 @@ import _import from 'eslint-plugin-import'
 import jest from 'eslint-plugin-jest'
 import prettier from 'eslint-plugin-prettier'
 import globals from 'globals'
-import path from 'node:path'
-import { fileURLToPath } from 'node:url'
 
-const __filename = fileURLToPath(import.meta.url)
-const __dirname = path.dirname(__filename)
 const compat = new FlatCompat({
-  baseDirectory: __dirname,
+  baseDirectory: import.meta.dirname,
   recommendedConfig: js.configs.recommended,
   allConfig: js.configs.all
 })
@@ -52,7 +48,16 @@ export default [
       sourceType: 'module',
 
       parserOptions: {
-        project: ['tsconfig.eslint.json']
+        projectService: {
+          allowDefaultProject: [
+            '__fixtures__/*.ts',
+            '__tests__/*.ts',
+            'eslint.config.mjs',
+            'jest.config.js',
+            'rollup.config.ts'
+          ]
+        },
+        tsconfigRootDir: import.meta.dirname
       }
     },
 
@@ -60,7 +65,7 @@ export default [
       'import/resolver': {
         typescript: {
           alwaysTryTypes: true,
-          project: 'tsconfig.eslint.json'
+          project: 'tsconfig.json'
         }
       }
     },