add Caddyfile, set up loopback and socat

rootfs/etc/caddy/Caddyfile

@@ -0,0 +1,3 @@
+localhost:3000 {
+	respond "Hello, world! I'm in an enclave :^)"
+}

rootfs/usr/local/bin/start.sh

@@ -1,4 +1,11 @@
 #!/bin/sh
 
-echo "Hello, world!"
-caddy --version
+echo "Configuring loopback network"
+busybox ip addr add 127.0.0.1/32 dev lo
+busybox ip link set dev lo up
+
+echo "Establishing socat listener"
+socat VSOCK-LISTEN:3000,reuseaddr,fork TCP:localhost:3000 &
+
+echo "Starting Caddy"
+caddy run --config /etc/caddy/Caddyfile