Ubuntu / Kubuntu 26.04 — vlc

For Ubuntu and Kubuntu 26.04, install vlc via apt instead of snap to access frame-by-frame controls. To enable SSH connections from older virtual machines to the host, install openssh-server and configure /etc/ssh/sshd_config.d/allow-older-clients.conf with specific Ciphers, KexAlgorithms, and HostKeyAlgorithms. Since the Kubuntu desktop uses Wayland, install the emacs-pgtk package rather than the standard emacs package to ensure proper window resizing, as emacs-pgtk utilizes pure GTK calls instead of mixing GTK and X11 calls.