Nymarub theme update

[Karma-Tsering]

Description

Implement Nyamrub's new blue color theme across the application, centralize the color definitions in a theme configuration (e.g., tailwind.config.js or CSS variables), replace all instances of the old golden-brown theme using a search-and-replace tool, update components to use the new theme dynamically, and test thoroughly to ensure consistent application across the UI.

Subtask

• Update all the colors.

[Karma-Tsering]

Test here : https://staging.nyamrub.monlam.ai

Check if the theme of staging is reflecting the latest approved design's theme

[Tendolls]

@Karma-Tsering this is the latest design https://www.figma.com/proto/zFpB2RdkH99yMgj3GkXyyP/Mock-for-BhashaDaan?page-id=596%3A5527&node-id=934-24251&node-type=frame&viewport=193%2C366%2C0.08&t=NxbSc9j8qfLrJQdl-1&scaling=contain&content-scaling=fixed

[TenzDelek]

• homepage and navbar mobile responsiveness
• about localization
  cc @Karma-Tsering