chore: introduce README.md

feat: sending Message::Terminate to the workers before calling join on each worker thread

feat: send and receive Message values and exiting the loop if a Worker receives Message::Terminate

feat: add Drop impl to ThreadPool and make worker threads optional for safe shutdown

feat: add a new trait FnBox to work around the current limitations of Box<FnOnce()>

feat: implement job execution in worker threads using boxed closures

feat: share job receiver across workers using Arc<Mutex<Receiver<Job>>>

feat: add job channel to ThreadPool and pass receiver to workers

refactor: introduce Worker struct and update ThreadPool to use workers instead of raw threads

feat: spawn and store worker threads in ThreadPool

feat: return Result from ThreadPool::new and introduce PoolCreationError

feat: introduce assert to handle thread size < 0 error

feat: add ThreadPool skeleton to lib.rs

chore: restructure project to separate binary and library

feat: introduce custom ThreadPool in main.rs