Switching away from app during slow post causes "the network connection was lost" error

[alexbbrown]

Describe the bug

Sometimes posting takes 30s. See #253.
If I temporarily switch to another app while this happens, I get a "the network connection was lost" error modal.

To Reproduce
Steps to reproduce the behavior:

1. Click reply on a post
2. Compose and tap post
3. If the spinner shows for a few seconds, switch app to eg safari
4. Return to metatext
5. Observe "the network connection was lost" modal appears

Expected behavior
if you switch to a different app while metatext is uploading a post or content, then back again, network connection should not be lost

technical note: URLSession supports downloading and uploading while app is in background. That might be a remediation to this issue

Screenshots
If applicable, add screenshots to help explain your problem.

(please complete the following information):

• Device: iPhone 12
• OS: iOS 16.1.1
• App Version: 1.7

Additional context
Add any other context about the problem here.

[alexbbrown]

[alexbbrown]

This can result in multiple posts, since after dismissing the "the network connection was lost", the post form is still presented, but it appears that the post can succeed anyway.