👾 [Other] - Update default colors in the Chat UI

[kalashshah]

Description

Update the default colors in the Chat UI. Need to update the colors mentioned below and fix mistakes in quite a few components throughout and confirm them with Zee.

    chatPreviewBackground: 'var(--gray-900)',
    userProfileBackground: 'var(--gray-900)',
    modalBackground: 'var(--gray-900)',
    criteriaLabelBackground: 'var(--gray-900)',
    chatWidgetModalBackground: 'var(--gray-900)',

Dapp Env

Prod (app.push.org), Staging (staging.push.org), Dev (dev.push.org)