[GNC] Backup to encrypted 7zip file

[flywire]

Simply put:
- I'm not the one using it
- it's to prevent casually or accidentally displaying the data
- considering the external value of personal cashbook data this very
accessible process kindly provided by a community member seems
fit-for-purpose
- GnuPG may well offer better security but it's not as turnkey
- if your employer is using a key-stroke logger then leave

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