Added new SCSS modules for layout, animations, colors, typography, and utilities.

[darshan-totagi]

• layout.scss: handles grid, flex, spacing, and responsive containers
• animations.scss: defines reusable transitions and keyframe effects
• colors.scss: stores theme color variables and palette mixins
• typography.scss: styles headings, paragraphs, and font utilities
• utilities.scss: includes helper classes for margins, padding, and visibility

These additions improve modularity and maintainability of the CSS structure.

• Have you followed the contributing guidelines?
• Have you explained what your changes do, and why they add value to the Guides?

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