Initial CV-aligned infrastructure portfolio

Rework portfolio around Linux operations, Zabbix monitoring, migration validation, and ELK/Grafana log observability.

Add AAP-style LVM resize workflow, Zabbix server/proxy/agent automation assets, Linux/AIX monitoring templates, and updated validation CI.

professional-infra/zabbix-monitoring-incident-response/docs/maintenance-runbook.md

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+# Zabbix Maintenance Runbook
+
+## Server Checks
+
+- Confirm Zabbix server process and web frontend availability.
+- Check database health, free space, and slow queries.
+- Review cache usage, poller utilization, and housekeeper activity.
+- Confirm recent values are arriving for representative Linux and AIX hosts.
+
+## Proxy Checks
+
+- Confirm proxy last seen timestamp.
+- Check proxy queue and delayed values.
+- Validate proxy database size and filesystem usage.
+- Confirm active/passive connectivity based on proxy mode.
+
+## Template Maintenance
+
+- Import templates in a controlled window.
+- Watch unsupported items after import.
+- Validate a small canary host group before wider rollout.
+- Document changed triggers and thresholds.
+
+## Common Failure Modes
+
+- Agent unreachable: check DNS, firewall, agent service, proxy route.
+- Unsupported item: check key spelling, OS capability, agent version, user parameter.
+- Proxy backlog: check WAN, DB size, proxy process, server availability.
+- Alert noise: review trigger thresholds and dependency design.