* feat(calculator): add new exercise to scripting piscine
* test(calculator): fix swapped exit codes for error handling
* docs(calculator): clarify function behavior for errors
* test(calculator): update error message for invalid number
* docs(calculator): add explicit case statement requirement
improve references section style
add case and getent examples
* fix(calculator): remove getent info in the subject
* chore(calculator): make the solution executable
* test(calculator): add check for case usage
* test(calculator): fix case statement usage check on wrong file
* fix(calculator): remove script added by error
revert changes committed by mistake on Dockerfile and entrypoint.sh
* style(calculator): add newline at end of file