cli (base): better background detection: - ANSI escape code detection is only used on terminals known to be compatible (currently xterm, konsole, and all VTE based ones) - `COLORFGBG` environment variable is used as fallback - if both methods fail, `dark` is used This should avoid problems with incompatible terminals (e.g. on QTerminal, users had to press `[ENTER]` each time). fix 406

[Desktop Entry]
Type=Application
Name=Libervia TUI (Primitivus)
Comment=console frontend for Libervia (XMPP)
Exec=libervia-tui
Icon=org.libervia.LiberviaTUI
Categories=Network;InstantMessaging;Chat;FileTransfer;RemoteAccess;
Keywords=xmpp;chat;messaging;im;file;sharing;communication;jabber;social;network;decentralization;console;