[BUG] Missing dependencies after `pip install -e .`

[Suyashd999]

What happened?

When installing Cortex in development mode using pip install -e ., not all required dependencies are installed. This causes ModuleNotFoundError at runtime when trying to import packages like requests, cryptography, and typing-extensions.

The issue occurs because:

1. Modern pip/setuptools prioritizes pyproject.toml over setup.py when both exist
2. pyproject.toml only defines 5 core dependencies (anthropic, openai, rich, pyyaml, python-dotenv)
3. requirements.txt contains 8 dependencies including the missing ones (requests, cryptography, typing-extensions)
4. When pip install -e . runs, it only installs what's in pyproject.toml, ignoring setup.py's attempt to read from requirements.txt

Additionally, there's duplication between requirements.txt, requirements-dev.txt, and pyproject.toml, creating maintenance overhead and potential for inconsistencies.

Impact

• New developers following setup instructions get broken installations
• cortex demo and other commands fail with ModuleNotFoundError: No module named 'requests'
• Dependency management is confusing with three separate files
• Risk of dependencies getting out of sync between files

Environment

• OS: Ubuntu 24.04 / Debian 12 / etc.
• Python: 3.11 / 3.12
• LLM Provider: Claude / OpenAI / Ollama