Document VM 102 security stack and update IPs to 192.168.1.105.

Add ARCHITECTURE.md and HOMELAB_IPS.md, refresh inventory and app configs
for Postgres, Neo4j, Homelab Command, pgAdmin, Homarr, and Homepage links.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -1,7 +1,10 @@
 # Private homelab — echte credentials (repo is privé op Gitea)
 
 NAS_IP=192.168.1.211
+# Proxmox VM 102 — Postgres, Neo4j, Homelab Command, syslog, NATS, security agent
+VM102_IP=192.168.1.105
 POSTGRES_USER=mo
+PG_HOST=192.168.1.105
 POSTGRES_PASSWORD=WaQTUw2t
 POSTGRES_DB=homelab
 PG_HOST_PORT=5433