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/oxidized/docker-compose.yml

@@ -0,0 +1,12 @@
+services:
+  oxidized:
+    image: oxidized/oxidized:0.30.1
+    container_name: oam-oxidized
+    environment:
+      - OXIDIZED_CONFIG=/home/oxidized/.config/oxidized/config
+      - TZ=America/Chicago
+    volumes:
+      - /opt/oam/oxidized/config:/home/oxidized/.config/oxidized
+    ports:
+      - "8083:8888"
+    restart: unless-stopped