Add VRRP failover infrastructure documentation (Nobara)

Deployed automatic failover for critical services (Traefik, Vaultwarden,
Authentik, AdGuard) from Unraid to Nobara workstation via Keepalived VRRP
with VIP 192.168.10.250. ~4 second failover time.

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

docs/04-HARDWARE-INVENTORY.md

@@ -160,12 +160,34 @@
 
 ---
 
+## Workstations
+
+### XTRM-Nobara | Nobara Linux Workstation
+
+| Property | Value |
+|----------|-------|
+| **Role** | Workstation + Failover Node |
+| **Location** | Main Bedroom |
+| **IP** | 192.168.10.103 |
+| **MAC** | 08:92:04:C6:07:C5 |
+| **OS** | Nobara Linux (Fedora 43 based) |
+| **CPU** | AMD Ryzen 9 6900HX (8C/16T) |
+| **RAM** | 16 GB |
+| **Storage** | 477GB NVMe (OS) + 1.8TB NVMe (btrfs pool with OS drive) |
+| **Network** | enp5s0 (2.5G Ethernet) |
+| **Switch Port** | CSS1-20 via PP1 M2 |
+| **SSH** | `ssh nobara` (key: ~/.ssh/id_ed25519_nobara) |
+
+**Failover Services:** Traefik, Vaultwarden, Authentik, AdGuard Home
+**Keepalived:** systemd service, BACKUP priority 100, VIP 192.168.10.250
+
+---
+
 ## End Devices (Wired)
 
 | Device | Room | Outlet | Switch Port | MAC |
 |--------|------|--------|-------------|-----|
 | LGTV | Living Room | L3 | CSS1-24 | - |
-| XTRM-Nobara | Main Bedroom | M2 | CSS1-20 | 08:92:04:C6:07:C5 |
 | Dell Display | Main Bedroom | M3 | CSS1-21 | - |
 | Dancho | Boys Room | B1 | CSS1-18 | - |
 | KVM Switch | - | Direct | CSS1-2 | - |