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>

server/packages.x86_64

@@ -0,0 +1,20 @@
+# Packages added to the Void base-system in the server live image.
+
+# Das OS Server: SSH, firewall, Docker, tools (see srcpkgs/das-server)
+das-server
+
+# Installer and the disk tools it uses, also kept by the installed system
+das-server-installer
+btrfs-progs
+cryptsetup
+dosfstools
+efibootmgr
+gptfdisk
+grub
+grub-x86_64-efi
+parted
+sudo
+xfsprogs
+
+# Virtual machine guests
+qemu-ga