Concurrency Fundamentals with Locks

Create and manage threads using `std::thread`.

Identify data races and race conditions in concurrent code.

Protect shared data using `std::mutex` and `std::lock_guard`.

Use `std::condition_variable` to signal between threads and prevent busy-waiting.

Implement a basic producer-consumer pattern using mutexes and condition variables.

Explain the performance cost of lock contention and false sharing.

Use thread-local storage for per-thread data.

Describe the 'observer effect' in performance measurement.