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/is-docker/index.d.ts

@@ -0,0 +1,13 @@
+/**
+Check if the process is running inside a Docker container.
+
+@example
+```
+import isDocker from 'is-docker';
+
+if (isDocker()) {
+	console.log('Running inside a Docker container');
+}
+```
+*/
+export default function isDocker(): boolean;