decommission: destroy plato (LXC 126)

LXC 126 stopped and destroyed on hubris. Remove all live references:
inventory, container doc, host file, README, containers index, auto-deploy
pipeline, DNS entry, SSH access table, nfs-export mount list.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

inventory.yaml

@@ -69,9 +69,6 @@ services:
   photos:
     url: https://photos.hubris.network
     backend: mule-images
-  plato:
-    url: https://plato.hubris.network
-    backend: plato
   arr_stack:
     backend: arriman
     note: jellyseerr / qbit / sab on docker compose
@@ -317,17 +314,7 @@ hosts:
     - /mnt/library
     age_pubkey: ''
   # 123 (claudio-bot) — destroyed 2026-06-04, replaced by Hermes Agent
-  plato:
-    kind: lxc
-    pve_id: 126
-    host: hubris
-    os: linux
-    role: app
-    lan_ip: 192.168.8.190
-    public_host: plato.hubris.network
-    mounts:
-    - /mnt/library/documents/plato
-    age_pubkey: ''
+  # 126 (plato) — destroyed 2026-06-28, notes workspace decommissioned
   zimaos:
     kind: vm
     pve_id: 100