[WIP] Add system architecture documentation (ARCHITECTURE.md)

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add system architecture documentation (ARCHITECTURE.md)</issue_title>
<issue_description>## 📐 Overview
The repository currently lacks a dedicated system architecture document.
Adding an ARCHITECTURE.md will help clearly explain the system design, major components, data flow, and architectural decisions.

This is important for:

• New contributors onboarding
• Code maintainability
• Technical reviews and interviews
• Long-term scalability and clarity

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🎯 Objective

Create a comprehensive ARCHITECTURE.md file that documents the overall system architecture in a clear and structured manner.

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🧱 Scope of Work

The ARCHITECTURE.md should include:

• High-level system overview
• Architecture style/pattern used
• Component-level breakdown
• Data flow explanation
• Technology stack
• Security considerations
• Scalability and future improvements
• (Optional) Architecture diagrams (ASCII / Mermaid)

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✅ Acceptance Criteria

• ARCHITECTURE.md added at repository root
• Clear explanation of system components
• Easy to understand for new contributors
• Uses Markdown formatting
• Diagrams included (if applicable)

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🔗 References

• README.md
• Project source code

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🏷️ Labels (Suggested)

documentation, architecture, enhancement
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add system architecture documentation (ARCHITECTURE.md) #6

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