fix: resolve Docker build failures and configuration issues

Add missing dependencies, fix Next.js config, update Docker Compose, and configure Tailwind CSS.

#VERCEL_SKIP

Co-authored-by: Anders Lehmann Pier <3219386+AndersPier@users.noreply.github.com>

postcss.config.js

@@ -0,0 +1,6 @@
+module.exports = {
+  plugins: {
+    tailwindcss: {},
+    autoprefixer: {},
+  },
+}