feat(oam): add LibreNMS agent deployment

Implement comprehensive check_mk agent deployment for LibreNMS monitoring:

- Create agent directory structure (/usr/lib/check_mk_agent/plugins, local, etc.)
- Deploy main check_mk_agent binary to /usr/bin
- Deploy distro script for OS detection
- Install systemd socket activation (check_mk.socket, check_mk@.service)
- Deploy monitoring plugins (smart, ntp-client, ntp-server, os-updates, postfix)
- Configure and enable check_mk socket for immediate monitoring

This enables centralised infrastructure monitoring through LibreNMS with
hardware health, NTP synchronisation, and mail queue visibility.

🤖 Generated with [Crush](https://github.com/charmassociates/crush)

Assisted-by: GLM-5 via Crush <crush@charm.land>

initializers/oam/apply

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # KNEL OAM Initializer
-# Sets up Operations and Maintenance tools
+# Sets up Operations and Maintenance tools including LibreNMS monitoring agents
 
 set -euo pipefail
 
@@ -13,4 +13,64 @@ if [[ -f ./scripts/up2date.sh ]]; then
     chmod +x /usr/local/bin/up2date.sh
 fi
 
+# Deploy LibreNMS check_mk agent
+if [[ -f ./librenms/check_mk_agent ]]; then
+    # Create agent directories
+    mkdir -p /usr/lib/check_mk_agent/plugins
+    mkdir -p /usr/lib/check_mk_agent/local
+    mkdir -p /etc/check_mk
+    mkdir -p /var/lib/check_mk_agent
+    
+    # Deploy main agent
+    cp ./librenms/check_mk_agent /usr/bin/check_mk_agent
+    chmod +x /usr/bin/check_mk_agent
+    
+    # Deploy distro script for OS detection
+    if [[ -f ./librenms/distro ]]; then
+        cp ./librenms/distro /usr/bin/distro
+        chmod +x /usr/bin/distro
+    fi
+    
+    # Deploy systemd service files
+    if [[ -f ./librenms/check_mk.socket ]]; then
+        cp ./librenms/check_mk.socket /etc/systemd/system/check_mk.socket
+    fi
+    
+    if [[ -f ./librenms/check_mk@.service ]]; then
+        cp ./librenms/check_mk@.service /etc/systemd/system/check_mk@.service
+    fi
+    
+    # Deploy plugins
+    for plugin in ./librenms/*.sh ./librenms/*.py; do
+        if [[ -f "$plugin" ]]; then
+            plugin_name=$(basename "$plugin")
+            cp "$plugin" /usr/lib/check_mk_agent/plugins/
+            chmod +x "/usr/lib/check_mk_agent/plugins/$plugin_name"
+        fi
+    done
+    
+    # Deploy other plugins (without extensions)
+    for plugin in ./librenms/smart ./librenms/ntp-client ./librenms/ntp-server.sh \
+                  ./librenms/os-updates.sh ./librenms/postfix-queues ./librenms/postfixdetailed \
+                  ./librenms/ups-nut.sh; do
+        if [[ -f "$plugin" ]]; then
+            plugin_name=$(basename "$plugin")
+            cp "$plugin" /usr/lib/check_mk_agent/plugins/
+            chmod +x "/usr/lib/check_mk_agent/plugins/$plugin_name"
+        fi
+    done
+    
+    # Deploy smart config if present
+    if [[ -f ./librenms/smart.config ]]; then
+        cp ./librenms/smart.config /etc/check_mk/smart.config
+    fi
+    
+    # Reload systemd and enable check_mk socket
+    systemctl daemon-reload
+    systemctl enable check_mk.socket
+    systemctl start check_mk.socket
+    
+    echo "LibreNMS agent deployed and enabled"
+fi
+
 echo "OAM initializer completed"