[docs] TrueNAS decommission cleanup — remove references from active docs

TrueNAS VM 9000 was operationally decommissioned 2026-04-13; NFS has been
served by Proxmox host (192.168.1.127) since. This commit scrubs remaining
references from active docs. VM 9000 itself remains on PVE in stopped state
pending user decision on deletion.

In-session cleanup already landed: reverse-proxy ingress + Cloudflare record
removed; Technitium DNS records deleted; Vault truenas_{api_key,ssh_private_key}
purged; homepage_credentials.reverse_proxy.truenas_token removed;
truenas_homepage_token variable + module deleted; Loki + Dashy cleaned;
config.tfvars deprecated DNS lines removed; historical-name comment added to
the nfs-truenas StorageClass (48 bound PVs, immutable name — kept).

Historical records (docs/plans/, docs/post-mortems/, .planning/) intentionally
untouched — they describe state at a point in time.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/runbooks/restore-full-cluster.md

@@ -8,8 +8,8 @@ Last updated: 2026-04-06
 - Proxmox host failure requiring fresh VM provisioning
 
 ## Prerequisites
-- Proxmox host (192.168.1.127) accessible
-- TrueNAS NFS server (10.0.10.15) accessible — or Synology NAS (192.168.1.13) for backups
+- Proxmox host (192.168.1.127) accessible, with NFS exports on `/srv/nfs` and `/srv/nfs-ssd`
+- Synology NAS (192.168.1.13) accessible for offsite backup restore if the PVE host backup disk is also lost
 - sda backup disk mounted at `/mnt/backup` on PVE host (or restore from Synology first)
 - Git repo with infra code
 - SOPS age keys for state decryption (`~/.config/sops/age/keys.txt`)