add the ansible playbooks for the monitoring stack

ansible/roles/prometheus/templates/prometheus.service.j2

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+[Unit]
+Description=Prometheus Monitoring System
+Documentation=https://prometheus.io/docs/
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=simple
+User=monitoring
+Group=monitoring
+ExecReload=/bin/kill -HUP $MAINPID
+ExecStart=/usr/local/bin/prometheus \
+  --config.file=/etc/prometheus/prometheus.yml \
+  --storage.tsdb.path=/var/lib/prometheus \
+  --storage.tsdb.retention.time=15d \
+  --web.listen-address=0.0.0.0:9090 \
+  --web.enable-lifecycle \
+  --log.level=info
+
+SyslogIdentifier=prometheus
+Restart=always
+RestartSec=5
+
+# Hardening
+NoNewPrivileges=true
+ProtectSystem=full
+ProtectHome=true
+
+[Install]
+WantedBy=multi-user.target

ansible/roles/prometheus/templates/prometheus.yml.j2

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+global:
+  scrape_interval: 30s
+  evaluation_interval: 30s
+  external_labels:
+    monitor: 'home-infra'
+    source: 'rpi'
+
+scrape_configs:
+  # Self-monitoring
+  - job_name: 'prometheus'
+    static_configs:
+      - targets: ['localhost:9090']
+        labels:
+          instance: 'rpi-prometheus'
+
+  # SNMP targets (network devices)
+{% if snmp_targets is defined and snmp_targets | length > 0 %}
+  - job_name: 'snmp'
+    scrape_interval: 60s
+    scrape_timeout: 30s
+    static_configs:
+{% for target in snmp_targets %}
+      - targets: ['{{ target.ip }}']
+        labels:
+          device: '{{ target.name }}'
+{% endfor %}
+    metrics_path: /snmp
+    relabel_configs:
+      - source_labels: [__address__]
+        target_label: __param_target
+      - source_labels: [__param_target]
+        target_label: instance
+      - target_label: __address__
+        replacement: localhost:9116
+    params:
+      module: [if_mib]  # Default module, can be overridden per-target
+{% endif %}
+
+  # Node exporter targets (VMs with node_exporter)
+{% if node_exporter_targets is defined and node_exporter_targets | length > 0 %}
+  - job_name: 'node'
+    static_configs:
+{% for target in node_exporter_targets %}
+      - targets: ['{{ target.ip }}:{{ target.port | default(9100) }}']
+        labels:
+          instance: '{{ target.name }}'
+{% endfor %}
+{% endif %}
+
+  # Proxmox PVE exporter
+{% if proxmox_targets is defined and proxmox_targets | length > 0 %}
+  - job_name: 'proxmox'
+    scrape_interval: 60s
+    static_configs:
+{% for target in proxmox_targets %}
+      - targets: ['{{ target.ip }}:{{ target.port | default(9221) }}']
+        labels:
+          instance: '{{ target.name }}'
+{% endfor %}
+    metrics_path: /pve
+    params:
+      module: [default]
+{% endif %}
+
+  # SNMP exporter self-metrics
+  - job_name: 'snmp-exporter'
+    static_configs:
+      - targets: ['localhost:9116']