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-inside-container/index.js

@@ -0,0 +1,23 @@
+import fs from 'node:fs';
+import isDocker from 'is-docker';
+
+let cachedResult;
+
+// Podman detection
+const hasContainerEnv = () => {
+	try {
+		fs.statSync('/run/.containerenv');
+		return true;
+	} catch {
+		return false;
+	}
+};
+
+export default function isInsideContainer() {
+	// TODO: Use `??=` when targeting Node.js 16.
+	if (cachedResult === undefined) {
+		cachedResult = hasContainerEnv() || isDocker();
+	}
+
+	return cachedResult;
+}