fix(hooks): abort the commit when npm test fails

pre-commit ran lint-staged and npm test but never checked their exit
codes, so a failing suite still produced a commit. set -e makes any
failing step abort.

.husky/pre-commit

@@ -1,4 +1,5 @@
 #!/usr/bin/env sh
+set -e
 
 # Auto-fix changed files and stage them
 npx --no-install lint-staged