feat(monitoring): enhance blackbox and alerting configurations

[Abasy714]

• Added new https_2xx module to blackbox.yml for monitoring public HTTPS endpoints.
• Updated alerting rules in alerts.yml to fix inverted logic for backend and public endpoint down alerts.
• Introduced new dashboards for backend API, PostgreSQL health, and uptime monitoring in Grafana.
• Created a new Prometheus alert rules file to define critical alerts for backend, PostgreSQL, and public endpoints.
• Updated Prometheus configuration to include alert rules and improved scrape configurations.
• Added Nginx configuration files for backend and frontend, including GeoIP2 support and SSL setup instructions.