docs: extract setup instructions into SETUP.md

[Aditya30ag]

Description of Changes

This Pull Request improves the project documentation by separating setup and build instructions from the main README.md into a dedicated SETUP.md file.

Related Issue

Closes #466

Type of Change

Please check the appropriate box that describes your PR:

• 🐛 Bug Fix — Fixes a documented issue or incorrect behavior
• ✨ Content Enhancement — Updates or improves existing content
• ✍️ New Content — Adds new chapters, examples, or significant sections
• 🛠️ Other — Please describe in the Description of Changes section

Additional Notes (Optional)

This is a documentation-only change. No code or functionality was modified.
Future updates to setup instructions can now be made independently of the README.

Checklist

• I have searched open pull requests to avoid duplicates.
• I have built the book locally using the build instructions and verified my changes work as expected.
• I have written clear, conventional commit messages, as per the Pull Request Guidelines.

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