Persist Easy Asterisk client exports to the docker directory

The vendor easy-asterisk script hardcodes /root for both export output
and its import file listing, but nothing was mounted there — exports
were being written to the container's ephemeral filesystem and lost on
recreate. Bind-mount ./exports to /root in both asterisk.sh and
asterisk-do.sh so exports/imports land under ~/docker/<service>/exports
on the host.

services/asterisk.sh

@@ -217,7 +217,7 @@ install_asterisk() {
 
     mkdir -p "$EA_DIR"
     mkdir -p "$EA_DIR/config/asterisk" "$EA_DIR/config/easy-asterisk" \
-             "$EA_DIR/logs" "$EA_DIR/spool" "$EA_DIR/lib"
+             "$EA_DIR/logs" "$EA_DIR/spool" "$EA_DIR/lib" "$EA_DIR/exports"
     ensure_docker_dir_ownership "$EA_DIR"
     cd "$EA_DIR" || return 1
 
@@ -320,6 +320,7 @@ services:
       - ./spool:/var/spool/asterisk
       - ./lib:/var/lib/asterisk
       - ./easy-asterisk.sh:/usr/local/bin/easy-asterisk:ro
+      - ./exports:/root
 CADDY_VOLUME_PLACEHOLDER
     env_file: .env
     restart: unless-stopped