feat(oam): port LibreNMS agent tooling from KNELServerBuild [#474]

Port the live LibreNMS monitoring patterns from the legacy
KNELServerBuild repo into oam/librenms-agent/, joining the existing
OAM tooling (oxidized, unpoller, smokeping, netdisco):

- agent/ — upstream check_mk agent + snmp-extend scripts (dmi, dpkg,
  mysql, ntp-client, ntp-server, os-updates, postfix, raspberry, smart,
  ss, ups-nut), copied verbatim (md5-verified), never to be edited here
- setup.sh — deploy module ported from ProjectCode/Modules/OAM/
  oam-librenms.sh; only the legacy framework bootstrap was replaced
  with plain bash (path constants + print_info -> echo)
- snmp-sudo.conf — Debian snmpd sudo rule the extends require
  (Debian-snmp NOPASSWD /bin/cat); carried as a file only, sudoers
  install is a policy decision per AGENTS.md

Lint gates: extend the existing upstream-skip mechanism for the
verbatim agent scripts (tests/shellcheck.sh + check-rules.sh prune,
same precedent as archive/provisioning/Agents/librenms), and fix the
stale skip path there (provisioning/ moved to archive/provisioning in
6244c1c; the bash extends have been failing the whole-repo shellcheck
gate since).

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

oam/librenms-agent/agent/ups-nut.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+################################################################
+# Instructions:                                                #
+# 1. copy this script to /etc/snmp/ and make it executable:    #
+#    chmod +x ups-nut.sh                                       #
+# 2. make sure UPS_NAME below matches the name of your UPS     #
+# 3. edit your snmpd.conf to include this line:                #
+#    extend ups-nut /etc/snmp/ups-nut.sh                       #
+# 4. restart snmpd on the host                                 #
+# 5. activate the app for the desired host in LibreNMS         #
+################################################################
+UPS_NAME="${1:-APCUPS}"
+
+PATH=$PATH:/usr/bin:/bin
+TMP=$(upsc $UPS_NAME 2>/dev/null)
+
+for value in "battery\.charge: [0-9.]+" "battery\.(runtime\.)?low: [0-9]+" "battery\.runtime: [0-9]+" "battery\.voltage: [0-9.]+" "battery\.voltage\.nominal: [0-9]+" "input\.voltage\.nominal: [0-9.]+" "input\.voltage: [0-9.]+" "ups\.load: [0-9.]+"
+do
+	OUT=$(echo "$TMP" | grep -Eo "$value" | awk '{print $2}' | LANG=C sort | head -n 1)
+	if [ -n "$OUT" ]; then
+		echo "$OUT"
+	else
+		echo "Unknown"
+	fi
+done
+
+for value in "ups\.status:[A-Z ]{0,}OL" "ups\.status:[A-Z ]{0,}OB" "ups\.status:[A-Z ]{0,}LB" "ups\.status:[A-Z ]{0,}HB" "ups\.status:[A-Z ]{0,}RB" "ups\.status:[A-Z ]{0,}CHRG" "ups\.status:[A-Z ]{0,}DISCHRG" "ups\.status:[A-Z ]{0,}BYPASS" "ups\.status:[A-Z ]{0,}CAL" "ups\.status:[A-Z ]{0,}OFF" "ups\.status:[A-Z ]{0,}OVER" "ups\.status:[A-Z ]{0,}TRIM" "ups\.status:[A-Z ]{0,}BOOST" "ups\.status:[A-Z ]{0,}FSD" "ups\.alarm:[A-Z ]"
+do
+    UNKNOWN=$(echo "$TMP" | grep -Eo "ups\.status:")
+    if [ -z "$UNKNOWN" ]; then
+        echo "Unknown"
+    else
+        OUT=$(echo "$TMP" | grep -Eo "$value")
+        if [ -n "$OUT" ]; then
+            echo "1"
+        else
+            echo "0"
+        fi
+    fi
+done
+
+UPSTEMP="ups\.temperature: [0-9.]+"
+OUT=$(echo "$TMP" | grep -Eo "$UPSTEMP" | awk '{print $2}' | LANG=C sort | head -n 1)
+[ -n "$OUT" ] && echo "$OUT" || echo "Unknown"
+