Switch backrest and filebrowser-colleen-hd to systemd automount bind mount

Replace Docker CIFS named volumes with bind mounts to /mnt/nas_backup,
which is managed by a systemd automount unit. This handles drive spin-down
reconnection independently of Docker container lifecycle.

backrest/docker-compose.yaml

@@ -1,13 +1,5 @@
 version: "3.8"
 
-volumes:
-  backup-mnt:
-    driver: local
-    driver_opts:
-      type: cifs
-      o: "addr=192.168.1.192,username=${SMB_USERNAME},password=${SMB_PASSWORD},vers=3.0,uid=0,gid=0,file_mode=0755,dir_mode=0755,iocharset=utf8,noperm,noserverino,echo_interval=300"
-      device: "//192.168.1.192/backup/nas-docker-data"
-    
 services:
   backrest:
     image: garethgeorge/backrest:latest
@@ -20,8 +12,7 @@ services:
       - /srv/backrest/tmp:/tmp
       - /srv/backrest/rclone:/root/.config/rclone # Mount for rclone config (needed when using rclone remotes)
       - /srv:/srv-data  # Mount local paths to backup
-      #- /mnt/backup-export:/backup-export # NFS share backup destination
-      - backup-mnt:/backup-export # NFS share backup destination
+      - /mnt/nas_backup/nas-docker-data:/backup-export
     environment:
       - BACKREST_DATA=/data
       - BACKREST_CONFIG=/config/config.json
@@ -30,4 +21,4 @@ services:
       - TZ=America/New_York
     ports:
       - "9898:9898"
-    restart: unless-stopped
+    restart: unless-stopped