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/linux-operations-automation/roles/hardening/README.md

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+# Hardening Role
+
+Apply security hardening to enterprise infrastructure nodes following CIS benchmarks.
+
+## Features
+
+- **CIS Compliance**: Support for CIS hardening levels 1 and 2
+- **SSH Hardening**: Disable root login, password auth, set auth limits
+- **Firewall Configuration**: UFW with configurable rules
+- **Service Cleanup**: Disable unnecessary services and remove insecure packages
+- **Handlers**: SSH restarts via handlers
+
+## Role Variables
+
+See `defaults/main.yml` for all available variables.
+
+### Key Variables
+
+- `cis_level`: CIS hardening level (1 or 2)
+- `disable_root_login`: Disable root SSH login (default: true)
+- `secure_ssh_config`: Apply SSH security hardening (default: true)
+- `firewall_policy`: Firewall default policy (default: deny)
+- `ssh_max_auth_tries`: Maximum SSH authentication attempts (default: 3)
+- `ssh_client_alive_interval`: SSH client alive interval in seconds (default: 300)
+- `ssh_allowed_networks`: Networks allowed SSH access from
+
+### SSH Allowed Networks
+
+Default trusted networks:
+- 10.0.0.0/8 (Private Class A)
+- 172.16.0.0/12 (Private Class B)
+- 192.168.0.0/16 (Private Class C)
+
+## Usage
+
+```yaml
+- role: hardening
+  vars:
+    cis_level: 1
+    disable_root_login: true
+    ssh_allowed_networks:
+      - 10.0.0.0/8
+      - 203.0.113.0/24
+```
+
+## SSH Configuration Changes
+
+- Root login disabled
+- Password authentication disabled
+- Maximum auth tries: 3
+- Empty passwords prohibited
+- Client alive interval: 300 seconds
+- Client alive count max: 2
+
+## Tags
+
+- `hardening`: All hardening tasks
+- `security`: Security-related tasks