K-9 Mail version 16.0

New:
- Default folder expansion behavior can be controlled by setting
- Preferred content type can be switched between text/plain and text/html

Fixed:
- Switching folders required too many clicks
- Fix edge-to-edge issues
- Application crashed at startup
- Application crashed on Pixel 10 Pro when returning to message list
- OAuth SMTP authentication failed with some Microsoft servers

Unresolved:
- Deleted/read messages in unified inbox may not update until refresh
