feat: add example attributions

[kpal81xd]

Description

• Adds @attribution parsing to example configs.
• Renders compact attribution rows beneath example instructions and in the mobile Info sheet.
• Adds attribution metadata to the gaussian splatting character controller examples.

Preview

Manual tests

• Opened the gaussian splatting first-person example in desktop layout and confirmed the attribution appears under the instructions with Source and license links.
• Opened the mobile Info sheet and confirmed the attribution appears there.

Checklist

• I have read the contributing guidelines
• My code follows the project coding standards
• This PR focuses on a single change