unit test `getTodos`

remove unnecessary line space

refactor unit test to use `XCTUnwrap()` for optionals

unit test `delete` functionality

write logic to prevent duplicate todo in the `todoList`

add test for not allowing duplicate todo in the list of todos

add unit test for `TodoCLIStore` `add` functionality

add unit test for the `Todo` model

Merge remote-tracking branch 'refs/remotes/origin/main'

add a new test file

update README

add more screenshot

usage screenshot

add some information about `TodoCLI` to the project

add `CheckCommand` logic to mark a todo as complete