Inventory cleanup; add ipt-server host_vars for all ipt hosts.

- hosts: remove unreachable/decommissioned hosts (file-ah-neu, file-ah-alt,
  file-km-neu, ga-al-gw-neu, gw-opp-neu, zapata-neu, zapata-alt, bbb-server,
  ki-fm, server28, ...) and duplicate aliases (etherpad = b.ns,
  cl-irights-neu = cl-irights, oolm-db = o21, devel-ruby = devel-todo).
- host_vars: add <short>-ipt-server.yml (fw_manage_config: false) for all
  hosts running the ipt-server firewall, generated by extract-fw-host-vars.py.
- host_vars: move/remove obsolete host directories, replace alias
  directories by symlinks (cl-lubax -> o32, cl-vbrg -> o34, oolm-db -> o21).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

host_vars/backup.oopen.de/backup-common.yml

@@ -289,6 +289,7 @@ default_user:
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIL7KbEZApiqEcU4aK3A2J8hy+r1uV7TZupwm4CHGqLPH root@ga-gh-gw'
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICCXqgmGcJfUDROAk24pTkQqddRj1sh1BW3JrbHu7ZtE root@ga-nh-gw'
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBaF9IsDzPo6nef47VbsLlqlmiwuLyFQ8Vawil/JPF9M root@ga-st-gw'
+      - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIK0kp3X3Qa/TD5XnVD9pkVj03F1EuG8g2SuhFceUKVk0 root@ga-st-mail'
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJPbony+4g4iFS32Cv/Bkmet4FsCAsrGTffwWm2eM16x root@git.warenform'
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIDqqmBWh3qmnx41NiLCn1LhVG0mn4++IUvRNC0OMh6h6 root@gitoea'
       - 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICR9o0+6jnfmXKOedKP6IZgt5lRIPFSJJ4FbMjz2SPkH root@gw-campus'