Update README

[softinio]

• update README
• add pyrefly as a dev dependency to pyproject.toml (for non-nix users benefit)

[Copilot]

Pull Request Overview

This PR refines the README by clarifying Option 2 when Python is already installed and introducing a new Option 3 for using the uv tool to install Python and dependencies.

• Clarified the Option 2 heading to mention preinstalled Python
• Added an Option 3 section with step-by-step uv usage instructions

Comments suppressed due to low confidence (2)

README.md:46

• Capitalize "Python" in the heading to maintain consistency with other references (e.g., "Ensure Python 3.13+").

#### Option 2: Without Nix (You already have python)

README.md:61

• Change to "2. Install Python using uv:" (capitalize "Python" and remove the extra space before the colon) for consistency and correct formatting.

2. Install python using uv  :