DOCS/FEAT: Add Monitoring System & Simulation Script Documentation; Introduce API Simulation Tool

[Morfusee]

1. Monitoring System Documentation

Added docs/monitoring-documentation.md:

• Detailed setup, configuration, and usage guide for the Prometheus-Grafana monitoring stack.
• Includes architecture diagrams, metrics catalog, PromQL query reference, alert rules, and operational procedures.
• Provides screenshots for verification of Prometheus and Grafana integration.

Added monitoring-related images in docs/images/:

• Architecture diagrams and dashboard screenshots for easy reference.

Updated docs/system-design-documentation.md:

• Now references the new monitoring documentation and reflects current use of Grafana and Prometheus.

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2. Simulation Script & Documentation

Added simulation/index.js:

• Node.js script that simulates typical user interactions with the API-based chat application for load testing and traffic simulation.
• Covers registration, login, chat creation, message sending, retrieval, update, and clean-up.

Added simulation/README.md and docs/simulation-documentation.md:

• Usage instructions, requirements, and troubleshooting guide for the simulation script.
• README provides a quick intro and links to the full guide.

Added simulation/.env.template:

• Template for required environment variables.

Added simulation/package.json and pnpm-lock.yaml:

• Ensures reproducible package management using pnpm.
• Declares dotenv as a dependency for environment management.

[hatudoggy]

Merging