[Good First Issue] 🎨 Add Community UI Themes (Catppuccin, Nord, Dracula, Gruvbox)

[ManishModak]

Summary

PCBuildSage supports custom JSON UI themes in data/themes/ that skin both the Next.js Web App and the interactive Terminal CLI.

Desired Themes to Add

• catppuccin-mocha.json (Dark pastel theme)
• nord-dark.json (Arctic blue dark theme)
• dracula.json (Vibrant dark purple theme)
• gruvbox-dark.json (Retro warm dark theme)

How to Contribute

1. Create a JSON file under data/themes/<theme-name>.json.
2. Define hex color tokens and ANSI terminal colors.
3. Validate WCAG AA contrast ratio standards locally:

   npm run validate:data

4. Submit a PR! See CONTRIBUTING.md for field specifications.