Feat auth header traefik

[thibaut1304]

Description

Added support for BasicAuth authentication for the Traefik service.

📌 Issue :
Currently, Homer does not allow sending an Authorization header to authenticate with Traefik.

✅ Solution :

• Checks if this.item.basic_auth is defined.
• Encode credentials in Base64 (btoa(user:password)).
• Adds the Authorization: Basic ... header to Traefik API requests.

🔥 Motivation :
Allows Traefik status to be correctly displayed even if authentication is required.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I've read & comply with the contributing guidelines
• I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.
• I have made corresponding changes to the documentation (README.md).
• I've checked my modifications for any breaking changes, especially in the config.yml file

[thibaut1304]

I forgot to mention in my PR that I also updated the documentation for the Traefik service in docs/customservices.md. This update explains how to configure Basic Auth in the config.yml file to authenticate requests.

[thibaut1304]

Closing in favor of #948 , which contains the same feature in a cleaner commit history.