Add devcontainer configuration for consistent development environment

[petersalomonsen]

Summary

Add a devcontainer configuration to provide a consistent development environment for all contributors using VS Code or GitHub Codespaces.

Details

A devcontainer configuration will ensure that all developers have the same tools, dependencies, and settings, regardless of their local environment. This is particularly useful for:

• New contributors who want to get started quickly
• Consistent Node.js and pnpm versions
• Pre-installed VS Code extensions for TypeScript development
• Consistent formatting and linting setup

Proposed Configuration

• Node.js LTS version
• pnpm package manager
• TypeScript and ESLint VS Code extensions
• Prettier extension for code formatting
• Git configuration
• Any other project-specific tools

Acceptance Criteria

• .devcontainer/devcontainer.json file created with appropriate configuration
• Dockerfile or base image specified for the development environment
• Required VS Code extensions listed
• Post-create commands to install dependencies
• Documentation updated to mention devcontainer support
• Tested in both VS Code and GitHub Codespaces