refactor: Remove RedHat/CentOS support, focus on Ubuntu/Debian

BREAKING CHANGE: Removed RedHat/CentOS/Rocky Linux support to improve stability

- Remove all RedHat/CentOS-specific code and variables
- Consolidate Ubuntu/Debian variables into single debian-family.yml
- Simplify CI/CD pipeline (remove CentOS tests)
- Remove unstable multi-OS complexity
- Update documentation to reflect Ubuntu/Debian focus
- Streamline playbooks for better maintainability

This change makes the project more stable and maintainable by focusing
on the most common server distributions (Ubuntu/Debian) instead of
trying to support multiple OS families with different package managers
and configurations.

playbooks/lemp-wordpress-ssl.yml

@@ -44,16 +44,7 @@
           - python3-certbot-nginx
         state: present
         update_cache: yes
-      when: enable_ssl and ansible_os_family == "Debian"
-      tags: ssl
-
-    - name: Install Certbot for Let's Encrypt (CentOS/RHEL)
-      yum:
-        name:
-          - certbot
-          - python3-certbot-nginx
-        state: present
-      when: enable_ssl and ansible_os_family == "RedHat"
+      when: enable_ssl
       tags: ssl
 
     - name: Check if SSL certificate exists