F: Backup fails when directory is missing - #1

Description

The challenge-f.sh backup script assumes that the backup directory already exists.

On a clean system, this causes the script to fail during the copy step, often without a clear explanation of what went wrong.

The script must proactively handle backup directory creation before any file operations occur.

Acceptance Criteria

• Check whether the backup directory exists at the start of the script
• Create the backup directory automatically if it does not exist
• Directory creation must be safe to run multiple times
• Print a clear, user-friendly message when the directory is created
• Do not attempt any file copy until the directory check is complete

Notes

• Manual directory creation by the user should never be required
• Directory validation should happen before any backup logic