♻️ Restructure: Move Astro to repository root

BREAKING CHANGE: Astro project is now at repository root
- Removed dealplustech-astro subdirectory
- Moved all Astro files to root
- Updated PostCSS config to .cjs
- Removed old Next.js files

✅ 11 pages built successfully
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✅ Ready for Easypanel deployment (no root dir needed)

Migration path:
- Old structure: /dealplustech-astro/
- New structure: / (root)

dealplustech-astro/node_modules/postcss/lib/at-rule.js

@@ -1,25 +0,0 @@
-'use strict'
-
-let Container = require('./container')
-
-class AtRule extends Container {
-  constructor(defaults) {
-    super(defaults)
-    this.type = 'atrule'
-  }
-
-  append(...children) {
-    if (!this.proxyOf.nodes) this.nodes = []
-    return super.append(...children)
-  }
-
-  prepend(...children) {
-    if (!this.proxyOf.nodes) this.nodes = []
-    return super.prepend(...children)
-  }
-}
-
-module.exports = AtRule
-AtRule.default = AtRule
-
-Container.registerAtRule(AtRule)