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/incident-response-runbook.md

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+# Incident Response Runbook
+
+## Filesystem Alert
+
+1. Confirm current usage and growth trend.
+2. Check whether the host is Linux or AIX and use the correct runbook.
+3. Validate application ownership of the filesystem.
+4. Clean known temporary paths or request LVM expansion when approved.
+5. Attach before/after evidence to the incident ticket.
+
+## Agent Unreachable
+
+1. Confirm whether data loss affects one host, one proxy, or one network segment.
+2. Check proxy queue and last seen timestamp.
+3. Validate agent service state and firewall path.
+4. For active checks, confirm `ServerActive` and hostname match.
+
+## Proxy Backlog
+
+1. Check server reachability from proxy.
+2. Check proxy DB filesystem usage.
+3. Confirm whether config sync recently changed.
+4. Reduce noise by temporarily disabling non-critical discovery rules if required.
+
+## Unsupported Items
+
+1. Identify affected template and item key.
+2. Check whether item is Linux-specific or AIX-specific.
+3. Validate agent version and custom user parameters.
+4. Roll back template change if canary host group is affected.

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.

professional-infra/zabbix-monitoring-incident-response/docs/proxy-design.md

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+# Zabbix Proxy Design
+
+## Purpose
+
+Zabbix proxies reduce dependency on direct connectivity between the central server and monitored hosts. They are useful for client networks, segmented environments, remote sites, and maintenance windows.
+
+## Active Proxy
+
+- Proxy connects to the Zabbix server.
+- Good for restricted networks where inbound access to the proxy is not allowed.
+- Hosts can use active agent checks against the proxy.
+- Main operational checks: proxy last seen, delayed values, local DB size, config sync.
+
+## Passive Proxy
+
+- Zabbix server connects to the proxy.
+- Useful when central server can reach the proxy network.
+- Requires firewall rules from server to proxy.
+- Main operational checks: proxy listener, network latency, poller load.
+
+## Operational Signals
+
+- Proxy queue growth.
+- Unsupported items after template changes.
+- Agent unreachable or active checks delayed.
+- Proxy DB growth during WAN outage.
+- Config sync failures after maintenance.