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/retext-stringify/lib/index.d.ts

@@ -0,0 +1,8 @@
+/**
+ * Add support for serializing natural language.
+ *
+ * @returns {undefined}
+ *   Nothing.
+ */
+export default function retextStringify(): undefined;
+export type Root = import('nlcst').Root;