Keep guest services off PBS hosts, refuse only known PBS in PVE scripts and follow the menu conventions

- On a PBS host the Monitor no longer starts the node metrics and VM prewarmers, the LXC update scheduler, the managed installs detector or the app update emitter, which read guests and PVE metrics that do not exist there
- pmx_require_pve refuses only a host known to be PBS, so an unreadable package list leaves the PVE scripts working as before
- The PBS menu numbers its options, shows the tables proxmox-backup-manager prints instead of raw JSON, and says Goodbye on exit
- The PBS update asks to press Enter before returning
- Spanish: Datastores de PBS

scripts/global/platform-functions.sh

@@ -8,8 +8,10 @@ pmx_is_pbs() {
     [[ "$(pmx_platform_field product)" == pbs ]]
 }
 
+# Only a host known to be PBS is refused: if the package list cannot be read,
+# the PVE scripts keep working as they did before PBS support.
 pmx_require_pve() {
-    if [[ "$(pmx_platform_field product)" != pve ]]; then
+    if pmx_is_pbs; then
         msg_error "$(translate 'This operation requires a Proxmox VE host. Use the PBS menu on Proxmox Backup Server.')"
         return 1
     fi