chore: initial import from KNEL/PFVCluster@041d311 [#769]

Split per O&M lane work order. Full history: KNEL/PFVCluster.
shellcheck debt fixed in librenms-agent (quoting, arithmetic, backticks);
fixes upstream ntp-server.sh bug: input_wakeups reported PACKETSENDFAILURES
instead of INPUTWAKEUPS. mysql.sh (PHP-in-.sh) exempt per house rule.

https://projects.knownelement.com/issues/769#note-4152

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