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/deployment.yml

@@ -0,0 +1,41 @@
+# NetDisco deployment configuration [#337]
+# SNMP community: kn3lmgmt (v2c)
+
+# Database connection (matched to docker-compose services)
+database:
+  host: netdisco-postgresql
+  dbname: netdisco
+  user: netdisco
+  pass: netdisco
+
+# SNMP authentication
+snmp_auth:
+  - tag: default_v2c
+    community: kn3lmgmt
+    read: true
+    write: false
+    version: 2
+
+  - tag: default_v1
+    community: kn3lmgmt
+    read: true
+    write: false
+    version: 1
+
+# Job scheduling
+schedule:
+  discoverall:
+    first: 60
+    every: 3600
+  macwalk:
+    first: 120
+    every: 900
+  arpwalk:
+    first: 150
+    every: 900
+  nbtwalk:
+    first: 180
+    every: 900
+
+# Node freshness (keep history)
+node_freshness: 0