docs: implement professional documentation structure and project hygiene

CONTRIBUTING.md

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+# Contributing to Plexus
+
+Thank you for your interest in contributing to Plexus!
+
+## 🤝 How to Contribute
+
+1. **Pick a Task**: Check the [Task Tracker](file:///home/sinan/Documents/repositories/local/plexus/docs/tasks.md) for open items.
+2. **Fork & Branch**: Create a new branch for your feature or bugfix.
+3. **Develop**: Follow the [Development Guide](file:///home/sinan/Documents/repositories/local/plexus/docs/development.md).
+4. **Test**: Ensure all tests pass.
+5. **Pull Request**: Submit a PR with a clear description of your changes.
+
+## 📜 Code of Conduct
+
+Please be respectful and collaborative. We aim to build a welcoming community for all developers.