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/mdast-util-to-markdown/lib/util/encode-character-reference.js

@@ -0,0 +1,11 @@
+/**
+ * Encode a code point as a character reference.
+ *
+ * @param {number} code
+ *   Code point to encode.
+ * @returns {string}
+ *   Encoded character reference.
+ */
+export function encodeCharacterReference(code) {
+  return '&#x' + code.toString(16).toUpperCase() + ';'
+}