fix: Fix product page syntax errors

1. Remove duplicate/broken code in product tables section
2. Fix PostCSS config for Tailwind 4
3. Add @tailwindcss/postcss dependency
4. Remove --production flag from Dockerfile (sharp required)

All fixes enable successful Docker build with favicon working.

node_modules/hast-util-to-html/lib/omission/util/siblings.js

@@ -0,0 +1,50 @@
+/**
+ * @import {Parents, RootContent} from 'hast'
+ */
+
+import {whitespace} from 'hast-util-whitespace'
+
+export const siblingAfter = siblings(1)
+export const siblingBefore = siblings(-1)
+
+/** @type {Array<RootContent>} */
+const emptyChildren = []
+
+/**
+ * Factory to check siblings in a direction.
+ *
+ * @param {number} increment
+ */
+function siblings(increment) {
+  return sibling
+
+  /**
+   * Find applicable siblings in a direction.
+   *
+   * @template {Parents} Parent
+   *   Parent type.
+   * @param {Parent | undefined} parent
+   *   Parent.
+   * @param {number | undefined} index
+   *   Index of child in `parent`.
+   * @param {boolean | undefined} [includeWhitespace=false]
+   *   Whether to include whitespace (default: `false`).
+   * @returns {Parent extends {children: Array<infer Child>} ? Child | undefined : never}
+   *   Child of parent.
+   */
+  function sibling(parent, index, includeWhitespace) {
+    const siblings = parent ? parent.children : emptyChildren
+    let offset = (index || 0) + increment
+    let next = siblings[offset]
+
+    if (!includeWhitespace) {
+      while (next && whitespace(next)) {
+        offset += increment
+        next = siblings[offset]
+      }
+    }
+
+    // @ts-expect-error: it’s a correct child.
+    return next
+  }
+}