borgbackup - how to automate on a modern MacOS

I run borgbackup as a non-privileged account on my Mac desktop to back up my home directory offsite. This worked fine up until recent versions of MacOS as long as full-disk access was enabled for bash (and maybe some other similar things, e.g. cron or launchd). But as of recent versions (I'm running MacOS Tahoe 26.5.1 now, but this problem popped up before that), I can't figure out a way to automate away accessing the "protected" directories.

I currently run the job via launchd. This is my standard nightly error:

```
/Users/ME/Documents: dir_open: [Errno 1] Operation not permitted: 'Documents'
E /Users/ME/Documents
/Users/ME/Downloads: dir_open: [Errno 1] Operation not permitted: 'Downloads'
E /Users/ME/Downloads
```

It doesn't go any better with cron.

I'm aware that this isn't really a problem with borgbackup itself, but it would be nice to find and document a working solution!