♻️ 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

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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/mdast-util-to-markdown/lib/handle/root.js

@@ -1,23 +0,0 @@
-/**
- * @import {Info, State} from 'mdast-util-to-markdown'
- * @import {Parents, Root} from 'mdast'
- */
-
-import {phrasing} from 'mdast-util-phrasing'
-
-/**
- * @param {Root} node
- * @param {Parents | undefined} _
- * @param {State} state
- * @param {Info} info
- * @returns {string}
- */
-export function root(node, _, state, info) {
-  // Note: `html` nodes are ambiguous.
-  const hasPhrasing = node.children.some(function (d) {
-    return phrasing(d)
-  })
-
-  const container = hasPhrasing ? state.containerPhrasing : state.containerFlow
-  return container.call(state, node, info)
-}