Add xterm-rio terminfo entry for better application compatibility

- Add xterm-rio as primary terminfo entry with rio as alias
- Applications that look for 'xterm-' prefixed terminals now work correctly
- Maintains TERM=rio environment variable for consistency
- Fixes crashes with termwiz-based applications like gitu
- Follows same pattern as other modern terminals (Alacritty, Ghostty)
- Updated build files and documentation to use both terminfo entries

Fixes #1190