Remove the outline on the portal logos including the favicon

[pedrominatel]

Description

This PR removes the outline on the logos used on the Developer Portal. This affects the UI when the icon is small and also adds consistency with other Espressif sites.

Related

Testing

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Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.

[pedrominatel]

@f-hollow, PTAL.

[f-hollow]

@pedrominatel

In addition to the icons you fixed, there are other icons with the outlines:

• assets/img/authors/espressif.png
• Other logos in assets/img/

If we look at it from the perspective of introducing the dark mode, it is not clear if we need to remove the outlines.

Can you please add to the description why you are making these updates and what problems they solve?

[pedrominatel]

@pedrominatel

In addition to the icons you fixed, there are other icons with the outlines:

* `assets/img/authors/espressif.png`

* Other logos in `assets/img/`

If we look at it from the perspective of introducing the dark mode, it is not clear if we need to remove the outlines.

Can you please add to the description why you are making these updates and what problems they solve?

@f-hollow, the images with the outlines should be used only in the dark mode. Since the implementation of the dark mode is still under discussion, we need to remove all logo images with outlines to keep consistency with our main portal.

[pedrominatel]

@f-hollow, for some reason, the preview job is not running.
PTAL on the latest changes.

[github-actions]

🎉 A preview for this PR is available at: https://preview-developer.espressif.com/pr479/