Add test script and CI workflow

- Add top-level test script that runs tests across all workspaces
- Add GitHub Actions workflow to run tests on PRs and merges to master

Co-authored-by: Ona <no-reply@ona.com>

package.json

@@ -7,6 +7,7 @@
 	],
 	"type": "module",
 	"scripts": {
+		"test": "bun run --filter '*' test",
 		"lint": "oxlint .",
 		"lint:fix": "oxlint --fix .",
 		"format": "oxfmt --write .",