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/zod/src/v4/classic/tests/void.test.ts

@@ -0,0 +1,12 @@
+import { expect, expectTypeOf, test } from "vitest";
+import * as z from "zod/v4";
+test("void", () => {
+  const v = z.void();
+  v.parse(undefined);
+
+  expect(() => v.parse(null)).toThrow();
+  expect(() => v.parse("")).toThrow();
+
+  type v = z.infer<typeof v>;
+  expectTypeOf<v>().toEqualTypeOf<void>();
+});