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.

.next/server/app-paths-manifest.json

@@ -0,0 +1,17 @@
+{
+  "/_not-found/page": "app/_not-found/page.js",
+  "/page": "app/page.js",
+  "/sitemap.xml/route": "app/sitemap.xml/route.js",
+  "/all-projects/page": "app/all-projects/page.js",
+  "/blog/[slug]/page": "app/blog/[slug]/page.js",
+  "/about-us/page": "app/about-us/page.js",
+  "/blog/page": "app/blog/page.js",
+  "/contact-us/page": "app/contact-us/page.js",
+  "/pipe/page": "app/pipe/page.js",
+  "/join-us/page": "app/join-us/page.js",
+  "/product/page": "app/product/page.js",
+  "/portfolio/page": "app/portfolio/page.js",
+  "/sales-engineer/page": "app/sales-engineer/page.js",
+  "/[...slug]/page": "app/[...slug]/page.js",
+  "/services/page": "app/services/page.js"
+}