docs: Add additional explanations and screenshots to steps

[FidelusAleksander]

This pull request includes updates to the development container configuration and multiple improvements to the GitHub Copilot tutorial documentation. The most important changes are summarized below.

Development Container Configuration:

• Updated the Python version in the devcontainer image from 3.9 to 3.13 and added port forwarding for port 8000 in .devcontainer/devcontainer.json.

GitHub Copilot Tutorial Documentation:

• Simplified instructions for creating a Codespace and clarified the use of default configurations in .github/steps/1-preparing.md.
• Added images and detailed instructions to enhance the user experience in .github/steps/1-preparing.md, including steps for running the project and accessing the application on port 8000.
• Included an example suggestion and detailed instructions for interacting with Copilot in .github/steps/2-first-introduction.md.
• Added images to illustrate the selection of AI models and generating commit messages with Copilot in .github/steps/2-first-introduction.md. [1] [2]
• Improved instructions for switching to Copilot Edits and added images for better guidance in .github/steps/3-copilot-edits.md. [1] [2]