introduce lint for client

Resolve #7998

scripts/lint.js

@@ -1,9 +1,17 @@
 const execa = require('execa');
 
 (async () => {
+	console.log('linting packages/backend ...');
 	await execa('npm', ['run', 'lint'], {
 		cwd: __dirname + '/../packages/backend',
 		stdout: process.stdout,
 		stderr: process.stderr,
 	});
+
+	console.log('linting packages/client ...');
+	await execa('npm', ['run', 'lint'], {
+		cwd: __dirname + '/../packages/client',
+		stdout: process.stdout,
+		stderr: process.stderr,
+	});
 })();