♻️ 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/mdast-util-to-markdown/lib/util/check-rule.js

@@ -1,21 +0,0 @@
-/**
- * @import {Options, State} from 'mdast-util-to-markdown'
- */
-
-/**
- * @param {State} state
- * @returns {Exclude<Options['rule'], null | undefined>}
- */
-export function checkRule(state) {
-  const marker = state.options.rule || '*'
-
-  if (marker !== '*' && marker !== '-' && marker !== '_') {
-    throw new Error(
-      'Cannot serialize rules with `' +
-        marker +
-        '` for `options.rule`, expected `*`, `-`, or `_`'
-    )
-  }
-
-  return marker
-}