Add editor formatting configuration for consistent contributions

[GaspardKirira]

It would be helpful to add a shared editor configuration for contributors, especially for VS Code.

Currently, contributors may get different formatting results depending on their local editor settings. Adding a .vscode/settings.json or .editorconfig file would make contributions cleaner and reduce formatting-only diffs.

Suggested scope:

• define indentation size
• define whether tabs or spaces are used
• configure format-on-save behavior if needed
• document the preferred formatter if the project has one
• optionally add a short note in the contribution docs

This would help keep pull requests focused on code changes instead of editor-specific formatting differences.