style: update examples sidebar styling

[kpal81xd]

Description

• Refresh the examples browser sidebar palette for category panels, headers, item backgrounds, and item text.
• Keep category panel borders visible with a softer color, clip panel contents to the rounded border, and add bottom spacing inside panels.
• Update examples lockfile metadata after npm-generated cleanup.

Manual tests: not run

Checklist

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

[mvaligursky]

I specifically added borders to make sections more obvious, please do not remove them.

[kpal81xd]

I specifically added borders to make sections more obvious, please do not remove them.

Ill add them back and fix the styling since it looked broken

[Maksims]

So many paddings :(

[Maksims]

The opposite of "minimal":

[mvaligursky]

but where's your style man! :)