Project: Building a C++ Thread Pool - Core Implementation

Define a clean public API for a thread pool, including methods for task submission and shutdown.

Design the internal architecture, identifying key components like the task queue, worker threads, and synchronization primitives.

Implement a thread-safe, blocking queue using `std::mutex` and `std::condition_variable` for tasks.

Implement the worker thread logic, including the main loop for fetching and executing tasks from the queue.

Integrate `std::packaged_task` or a similar mechanism to handle tasks with return values.

Use `std::future` to provide a mechanism for clients to retrieve results from submitted tasks.

Implement a graceful shutdown mechanism that waits for pending tasks to complete.

Set up a testing framework (e.g., Google Test) and write unit tests for the thread-safe queue and task submission.