Add ts-jest and Grid tests

- mostly for practice with jest
- but also if I add new Grid features I can use this in development

eslint.config.mjs

@@ -15,7 +15,13 @@ export default tseslint.config(
     },
   },
   {
-    ignores: ['eslint.config.mjs', 'prettier.config.mjs', 'lint-staged.config.mjs', 'src/utils/template/index.ts']
+    ignores: [
+      'eslint.config.mjs',
+      'lint-staged.config.mjs',
+      'jest.config.mjs',
+      'prettier.config.mjs',
+      'src/utils/template/index.ts'
+    ]
   },
   eslint.configs.recommended,
   tseslint.configs.recommendedTypeChecked,

jest.config.mjs

@@ -0,0 +1,14 @@
+import { createDefaultEsmPreset } from 'ts-jest';
+
+/** @type {import('ts-jest').JestConfigWithTsJest} **/
+export default {
+  ...createDefaultEsmPreset(),
+  testEnvironment: "node",
+  transform: {
+    "^.+.tsx?$": ["ts-jest",{}],
+  },
+  moduleNameMapper: {
+    "^utils/(.*)$": "<rootDir>/src/utils/$1",
+  },
+  resolver: "ts-jest-resolver",
+};