Improve README Structure, Add Architecture Diagram and API Documentation

[Nitya-003]

Description:

The current README.md for Pinicker provides a great functional overview. However, since the project involves a split architecture (Python Backend + Flutter/Mobile Client), the documentation needs to be more structured to help contributors set up both environments without confusion.

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Proposed Enhancements:

1. Architecture Visualization:

• Add a flow diagram showing the interaction between Pinterest API ↔️ Python Backend ↔️ Mobile App ↔️ WhatsApp. This helps developers understand how the SQLite database prevents duplicates.

2. Detailed API Specs:

• Document the internal endpoint (e.g., GET /check-new-stickers) that the mobile app uses to communicate with the Flask server.
• Include expected JSON response formats.

3. Visual "How it Works" Section:

• Add a section for "App Screenshots" or "UI Mockups" to show what the "Add to WhatsApp" button looks like.

4. Enhanced Setup Guide:

• Split the installation guide into two clear sections: Backend Setup and Mobile Setup.
• Add a `.env.example template for Pinterest API keys and Board IDs.

5. Troubleshooting & Requirements:

• Explicitly mention the WhatsApp 3-sticker minimum requirement in a "Warning" or "Note" callout box.
• Add information about network configuration (e.g., ensuring the phone and server are on the same Wi-Fi).

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Why this is needed?

• Cross-stack development: Since this project uses both Python and Flutter, clear boundaries in the documentation are essential.
• Onboarding: New contributors can quickly identify which part (Backend or App) they want to work on.

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Tasks for Contributors:

• Add a Mermaid.js diagram for the data flow.
• Format the "Future Enhancements" into a cleaner Roadmap.
• Add a "Prerequisites" section (Python 3.x, Flutter SDK, Pinterest Dev Account).
• Use GitHub Markdown alerts (> [!NOTE]) for important WhatsApp limitations.

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I will love to work on this issue and Submit a PR regarding the same.

Labels: SWOC SWOC'26 good first issue documentation