Fix the Lock That Never Releases

Add __exit__ so a resource lock always releases, even after a crash.

A advanced Linux challenge worth 20 points. Solve it hands-on in a real Linux environment in your browser - no local setup, no fake shells.

The Challenge

Scenario: /home/labuser/lab/resource_lock.py defines a ResourceLock context manager whose __enter__ locks a resource, but it has no __exit__ at all - the lock never releases, even after the code inside with finishes or crashes.

Task: Add __exit__ so status.txt always ends up UNLOCKED, both on a normal run and when the code inside with raises an exception. Run check when ready.