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/readme.md

@@ -0,0 +1,27 @@
+# is-docker
+
+> Check if the process is running inside a Docker container
+
+## Install
+
+```
+$ npm install is-docker
+```
+
+## Usage
+
+```js
+import isDocker from 'is-docker';
+
+if (isDocker()) {
+	console.log('Running inside a Docker container');
+}
+```
+
+## CLI
+
+```
+$ is-docker
+```
+
+Exits with code 0 if inside a Docker container and 2 if not.