Add dynamic themes with Tailwind CSS and e-commerce template

[Josephat-S]

added Tailwind CSS dynamic themes and created e-commerce template
This pull request scaffolds a new Next.js 14 monolith template for an e-commerce store, providing a modern, themeable UI foundation and all necessary configuration for development. It also enhances the portfolio template to use the same theme system for consistency. The most important changes are grouped below.

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New E-commerce Next.js Monolith Template:

• Adds a complete new template under templates/ecommerce/nextjs-monolith, including initial pages (app/page.tsx, app/products/page.tsx, app/products/[slug]/page.tsx) with placeholder content and navigation structure. [1] [2] templates/ecommerce/nextjs-monolith/app/products/[slug]/page.tsxR1-R38, [3]
• Implements a theme system with CSS variables for light, glassmorphism, and dark terminal themes in app/globals.css, and ensures global application of these variables.
• Configures Tailwind CSS to use theme variables and sets up PostCSS, ESLint, TypeScript, and Next.js config files for a ready-to-develop environment (tailwind.config.ts, postcss.config.js, .eslintrc.json, tsconfig.json, next.config.js, package.json). [1] [2] [3] [4] [5] [6]

Portfolio Template Theme Consistency:

• Updates the portfolio template's globals.css and Tailwind config to use the same theme variable system as the e-commerce template, ensuring consistent theming and easier maintenance. [1] [2]
• Refactors the portfolio home page to use the new theme classes and variables for colors, backgrounds, and border radii.

Closes #14

Closes #13