feat(releng): add fws-recovery-boot systemd service

Add systemd service unit for FWS system recovery boot mode. This service handles recovery session initialization on tty1 with fallback from GUI (via startx/openbox) to console assistant if graphical startup fails. The service is only activated via fws-recovery.target kernel command line parameter and does not interfere with normal boot processes.

configs/releng/airootfs/etc/systemd/system/fws-recovery-boot.service

@@ -0,0 +1,24 @@
+[Unit]
+Description=FWS - Reparation du systeme (session de secours sur tty1)
+# Demarre UNIQUEMENT via fws-recovery.target (entree GRUB « Reparer FWS » du
+# systeme installe : systemd.unit=fws-recovery.target). PAS de [Install] :
+# enrole dans aucun boot normal, donc son Conflicts=getty@tty1 ne peut jamais
+# casser le login tty1 d'un boot ordinaire.
+# Sur le live, c'est /root/.zprofile (autologin tty1) qui gere la reparation.
+ConditionKernelCommandLine=fws.recovery=1
+ConditionPathExists=!/run/archiso
+Conflicts=getty@tty1.service display-manager.service
+After=systemd-user-sessions.service getty@tty1.service display-manager.service
+
+[Service]
+Type=idle
+# GUI via startx (openbox + fws-recovery-gui) ; si X ne demarre pas (pilote
+# video casse — un cas de reparation typique), repli sur l'assistant CONSOLE.
+ExecStart=/bin/sh -c '/usr/bin/startx /usr/local/bin/fws-recovery-session -- vt1 || exec /usr/local/bin/fws-recovery'
+StandardInput=tty
+StandardOutput=tty
+StandardError=tty
+TTYPath=/dev/tty1
+TTYReset=yes
+TTYVHangup=yes
+Restart=no