Stage 6: server image with a console installer (0.4.0)

- server/ profile and build-iso.sh [desktop|server]; make iso-server,
  make qemu-server, run-qemu.sh --serial; login on tty and ttyS0
- das-server: SSH, chrony, NetworkManager/dhcpcd, Docker with Compose,
  nftables (closed except SSH, own table), fail2ban reading socklog,
  sshd without root passwords, Docker log rotation, tools
- das-server-install: dialog installer in Ukrainian and English, or
  unattended with --config; GPT + Btrfs subvolumes, GRUB for UEFI and BIOS,
  serial console, SSH key with optional keys-only logins
- das-install-common: mount-source and postinstall shared with Calamares
- dsv: runit service manager (list, enable, disable, start, stop,
  restart, status, logs) with bash completion, also on the desktop
- das-update split into a subpackage without GTK; the window and tray
  icon move to /usr/libexec/das/das-update-gui
- das-snapper-setup enables dbus, which snapper needs
- TODO: ISO size review with measured numbers and options

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

srcpkgs/das-snapshots/files/das-snapper-setup

@@ -43,7 +43,9 @@ if [ -f "$cfg" ] && ! grep -q '^GRUB_BTRFS_SUBMENUNAME=' "$cfg"; then
 fi
 
 # Hourly snapshots come from cron, and grub-btrfs adds them to the boot menu.
-for sv in cronie grub-btrfs; do
+# snapper talks to snapperd over the system bus (the server has no desktop
+# that would enable dbus).
+for sv in dbus cronie grub-btrfs; do
 	ln -sfn "/etc/sv/$sv" "/etc/runit/runsvdir/default/$sv"
 done
 msg "snapshots are enabled"