fix(site): simplify error details and remove SHOW_ERROR_DETAILS flag

- Remove SHOW_ERROR_DETAILS and PUBLIC_VERCEL_ENV constants; always
  show error details when present
- Remove hasErrorDetails variable; inline the check directly
- Simplify pre content rendering: remove complex ternary, use
  straightforward JSX expressions per reviewer suggestion

Author: ZeroPointSix

apps/site/app/[locale]/error.tsx

@@ -4,7 +4,6 @@ import { useTranslations } from 'next-intl';
 
 import Button from '#site/components/Common/Button';
 import GlowingBackdropLayout from '#site/layouts/GlowingBackdrop';
-import { SHOW_ERROR_DETAILS } from '#site/next.constants.mjs';
 
 import type { FC } from 'react';
 
@@ -14,7 +13,6 @@ type ErrorPageProps = {
 
 const ErrorPage: FC<ErrorPageProps> = ({ error }) => {
   const t = useTranslations();
-  const hasErrorDetails = Boolean(error.message || error.digest);
 
   return (
     <GlowingBackdropLayout kind="default">
@@ -28,17 +26,15 @@ const ErrorPage: FC<ErrorPageProps> = ({ error }) => {
         {t('layouts.error.internalServerError.description')}
       </p>
 
-      {SHOW_ERROR_DETAILS && hasErrorDetails && (
+      {(error.message || error.digest) && (
         <details className="max-w-2xl rounded-lg border border-neutral-300 bg-neutral-950/90 px-4 py-3 text-left text-neutral-50">
           <summary className="cursor-pointer font-medium">
             {t('layouts.error.details')}
           </summary>
 
           <pre className="mt-3 overflow-x-auto font-mono text-xs leading-6 break-words whitespace-pre-wrap">
             {error.message}
-            {error.digest
-              ? `${error.message ? '\n' : ''}digest: ${error.digest}`
-              : ''}
+            {error.digest && `digest: ${error.digest}`}
           </pre>
         </details>
       )}

apps/site/next.constants.mjs

@@ -14,18 +14,6 @@ export const IS_DEV_ENV = process.env.NODE_ENV === 'development';
  */
 export const VERCEL_ENV = process.env.VERCEL_ENV || undefined;
 
-/**
- * Public-facing Vercel environment, safe to use in client-side code.
- */
-export const PUBLIC_VERCEL_ENV =
-  process.env.NEXT_PUBLIC_VERCEL_ENV || VERCEL_ENV;
-
-/**
- * Error details should only be exposed in local development or Vercel preview
- * deployments, never in production.
- */
-export const SHOW_ERROR_DETAILS = IS_DEV_ENV || PUBLIC_VERCEL_ENV === 'preview';
-
 /**
  * This is used for telling Next.js to do a Static Export Build of the Website
  *