Correct Ana-side NAS identity: Debian 12, not TrueNAS

Network probes (no web admin, Debian SSH banner, only file-server ports
open) show 10.250.50.50 is vanilla Debian 12 with hand-configured NFS/SMB,
reprovisioned from the original TrueNAS SCALE install. Update stack
comments, README storage notes, Backrest description, proxmox-vms.md
entry for VM 100, and the restic configs intro to match.

Cross-site sync plan simplifies to plain rsync over SSH on both sides —
no appliance-specific tooling needed.

servers/ana-docker/README.md

@@ -14,7 +14,7 @@ General-purpose Docker host for the Anaheim colo. Runs everything at `10.250.0.0
 - **CPU:** 8 vCPU (QEMU virtual — this is a VM)
 - **RAM:** 15.6 GB
 - **GPUs:** none
-- **Storage:** 245 GB root (ext4) + NFS mounts from `10.250.50.50` (TrueNAS)
+- **Storage:** 245 GB root (ext4) + NFS mounts from `10.250.50.50` (Debian 12 NFS/SMB file server; historically TrueNAS SCALE, since reprovisioned)
 - **OS:** Debian 12 (bookworm), kernel 6.1.x
 - **Docker:** 20.10.24
 
@@ -47,7 +47,7 @@ General-purpose Docker host for the Anaheim colo. Runs everything at `10.250.0.0
 | dockge | 5001 | Docker stack management UI |
 | beszel | 8090 | Fleet metrics hub (+ local agent); agents on the other hosts report here |
 | dozzle (hub as `dozzle-hub`) | 8088 | Fleet log viewer; agents on the other hosts report here |
-| restic rest-server | 8000 | Anaheim-side restic endpoint (writes to TrueNAS NFS at `/mnt/backup/restic/repo/ana/`); paired with `rest-server-nh3` on the Synology for the NH3 side |
+| restic rest-server | 8000 | Anaheim-side restic endpoint (writes to the NFS mount at `/mnt/backup/restic/repo/ana/`, backed by the Debian file server at `10.250.50.50`); paired with `rest-server-nh3` on the Synology for the NH3 side |
 | backrest | 9898 | Fleet-wide restic snapshot viewer / restore UI — points at both rest-servers |
 | it-tools | 8780 | Dev utilities |
 | mattermost | — | Stopped; kept around for reference |