Automatic Backup System for Project Files

Story: As a user, I want the system to create a backup file every 15 minutes or according to the specified interval within the Settings in Sigma. This backup file should be maintained within the project directory without causing any disruption or noticeable delay in the user interface while saving.

Acceptance Criteria:

1. The backup file should only be stored within the project directory as a system file - so that the user can NOT see the files unless they disable the function ("Hide protected operating system files") in the pathfinder.

2. The backup process should not disrupt or delay the user's ongoing work or file-saving process - eg. using other threads.

3. The backup process should operate whether or not the file has been saved

Notes: Currently, the functionality works as follows:

1. Saving the calculation.

2. Making a change in the calculation.

3. Waiting for 15 minutes (or at the specified interval made in Settings) without making any further changes.

4. After this period, a system file is saved in the project directory.

5. If the user then saves their calculation again, the backup file is moved to this path (C:\Users\%userprofile%\AppData\Local\Temp\SigmaRecovery).