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.

easypanel.config.json

@@ -0,0 +1,16 @@
+{
+  "easypanel": {
+    "url": "",
+    "project": "customerwebsite",
+    "app": {
+      "name": "dealplustech-astro",
+      "port": 4321,
+      "image": "dealplustech-astro:latest"
+    },
+    "env": {
+      "NODE_ENV": "production",
+      "PORT": "4321",
+      "HOST": "0.0.0.0"
+    }
+  }
+}