refactor: Move Astro project to root directory

- Move all Astro files from dealplustech-astro/ to root
- Archive Next.js code in _nextjs-backup/
- Update .gitignore for Astro project
- Simplify project structure

This completes the migration from Next.js to Astro.
The Astro project is now at the root level.

package.json

@@ -1,47 +0,0 @@
-{
-  "name": "dealplustech",
-  "version": "1.0.0",
-  "private": true,
-  "scripts": {
-    "dev": "next dev",
-    "build": "next build",
-    "start": "next start",
-    "lint": "next lint"
-  },
-  "dependencies": {
-    "axios": "^1.13.5",
-    "cheerio": "^1.2.0",
-    "clsx": "^2.1.1",
-    "gray-matter": "^4.0.3",
-    "next": "14.2.3",
-    "playwright": "^1.58.2",
-    "react": "^18.3.1",
-    "react-dom": "^18.3.1",
-    "remark": "^15.0.1",
-    "remark-gfm": "^4.0.1",
-    "remark-html": "^16.0.1",
-    "tailwind-merge": "^2.3.0"
-  },
-  "devDependencies": {
-    "@tailwindcss/typography": "^0.5.19",
-    "@types/node": "^20.12.12",
-    "@types/react": "^18.3.2",
-    "@types/react-dom": "^18.3.0",
-    "autoprefixer": "^10.4.19",
-    "eslint": "^8.57.0",
-    "eslint-config-next": "14.2.3",
-    "postcss": "^8.4.38",
-    "tailwindcss": "^3.4.3",
-    "typescript": "^5.4.5"
-  },
-  "description": "Complete redesign of dealplustech.co.th website built with Next.js 14, TypeScript, and Tailwind CSS.",
-  "main": "index.js",
-  "repository": {
-    "type": "git",
-    "url": "https://git.moreminimore.com/kunthawat/dealplustech.git"
-  },
-  "keywords": [],
-  "author": "",
-  "license": "ISC",
-  "type": "commonjs"
-}