feat(oam): deploy Smokeping, NetDisco, Oxidized, UNPoller on tsys-librenms [#337][#375]

Deploy OAM monitoring stack on tsys-librenms VM:

- Smokeping: fully operational (port 8081, 16 targets, FPing probing)
- NetDisco: backend+DB+PostgreSQL running (port 8082), all 4 Dell switches
  discovered via SNMP. Web UI blocked by Dancer session_cookie_key config
  issue — needs interactive netdisco-deploy run
- Oxidized: container running (port 8083), deployed with placeholder
  credentials — needs switch login/password to start config backups
- UNPoller: config + docker-compose ready, blocked on Docker image
  availability (image moved from all common registries)
- Weathermap: not yet started (deferred to separate commit)

All configs use DNS names only (no IP literals). All scripts pass
shellcheck via check-rules.sh.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

oam/netdisco/docker-compose.yml

@@ -0,0 +1,44 @@
+services:
+  netdisco-postgresql:
+    image: netdisco/netdisco:2.102001-postgresql
+    container_name: oam-netdisco-db
+    environment:
+      - POSTGRES_USER=netdisco
+      - POSTGRES_PASSWORD=netdisco
+      - POSTGRES_DB=netdisco
+    volumes:
+      - /opt/oam/netdisco/pgdata:/var/lib/postgresql/data
+    restart: unless-stopped
+
+  netdisco-backend:
+    image: netdisco/netdisco:2.102001-backend
+    container_name: oam-netdisco-backend
+    depends_on:
+      - netdisco-postgresql
+    environment:
+      - NETDISCO_DB_HOST=netdisco-postgresql
+      - NETDISCO_DB_NAME=netdisco
+      - NETDISCO_DB_USER=netdisco
+      - NETDISCO_DB_PASS=netdisco
+      - NETDISCO_SNMP_COMMUNITY=kn3lmgmt
+    volumes:
+      - /opt/oam/netdisco/config/deployment.yml:/home/netdisco/environments/deployment.yml
+      - /opt/oam/netdisco/data:/home/netdisco/netdisco-sqlite
+    restart: unless-stopped
+
+  netdisco-web:
+    image: netdisco/netdisco:2.102001-web
+    container_name: oam-netdisco-web
+    depends_on:
+      - netdisco-postgresql
+      - netdisco-backend
+    environment:
+      - NETDISCO_DB_HOST=netdisco-postgresql
+      - NETDISCO_DB_NAME=netdisco
+      - NETDISCO_DB_USER=netdisco
+      - NETDISCO_DB_PASS=netdisco
+    ports:
+      - "8082:5000"
+    volumes:
+      - /opt/oam/netdisco/config/deployment.yml:/home/netdisco/environments/deployment.yml
+    restart: unless-stopped