feat: assemble an installable Gentoo live image in an exported rootfs

image/rootfs/etc/hydra/defaults.toml

@@ -0,0 +1,5 @@
+network = "bridge"
+bridge = "hydrabr0"
+width = 1920
+height = 1080
+refresh_millihz = 144000

image/rootfs/etc/hydra/dnsmasq.conf

@@ -0,0 +1,11 @@
+interface=hydrabr0
+bind-dynamic
+except-interface=lo
+listen-address=10.203.0.1
+dhcp-range=10.203.0.20,10.203.0.254,255.255.255.0,12h
+dhcp-option=option:router,10.203.0.1
+dhcp-option=option:dns-server,10.203.0.1
+dhcp-leasefile=/var/lib/hydra/dnsmasq.leases
+resolv-file=/run/NetworkManager/resolv.conf
+domain-needed
+bogus-priv

image/rootfs/etc/hydra/live-mode/active

@@ -0,0 +1 @@
+HydraOS live medium: changes to the host root are not persistent.

image/rootfs/etc/hydra/live-mode/remove-on-install.json

@@ -0,0 +1,7 @@
+[
+  "/etc/greetd/live.toml",
+  "/etc/sudoers.d/90-hydra-live",
+  "/etc/systemd/system/greetd.service.d/90-hydra-live.conf",
+  "/etc/systemd/system/getty@tty2.service.d/90-hydra-live.conf",
+  "/etc/systemd/system/serial-getty@ttyS0.service.d/90-hydra-live.conf"
+]