fix(netlify): harden server env fallback and disable Vercel analytics on Netlify

- update server env resolver to read Netlify runtime env safely
  (supports both globalThis.Netlify and global Netlify identifier)
- keep process.env as primary source, Netlify env as fallback
- render @vercel/analytics only on Vercel (VERCEL=1) to avoid Netlify 404s

Author: LesiaUKR

frontend/app/layout.tsx

@@ -89,7 +89,7 @@ export default function RootLayout({
         className={`${geistSans.variable} ${geistMono.variable} bg-gray-50 text-gray-900 antialiased transition-colors duration-300 dark:bg-neutral-950 dark:text-gray-100`}
       >
         {children}
-        {process.env.NODE_ENV === 'production' && <Analytics />}
+        {process.env.VERCEL === '1' && <Analytics />}
       </body>
     </html>
   );

frontend/lib/env/server-env.ts

@@ -4,14 +4,30 @@ type NetlifyEnv = {
   get?: (key: string) => string | undefined;
 };
 
+type NetlifyRuntime = {
+  env?: NetlifyEnv;
+};
+
+declare const Netlify: NetlifyRuntime | undefined;
+
+function getNetlifyRuntime(): NetlifyRuntime | undefined {
+  const fromGlobalThis = (globalThis as { Netlify?: NetlifyRuntime }).Netlify;
+  if (fromGlobalThis) return fromGlobalThis;
+
+  if (typeof Netlify !== 'undefined') return Netlify;
+
+  return undefined;
+}
+
 function readFromNetlifyEnv(key: string): string | undefined {
-  const maybeNetlify = (globalThis as { Netlify?: { env?: NetlifyEnv } }).Netlify;
-  const value = maybeNetlify?.env?.get?.(key);
+  const runtime = getNetlifyRuntime();
+  const value = runtime?.env?.get?.(key);
   return typeof value === 'string' && value.trim() ? value.trim() : undefined;
 }
 
 export function readServerEnv(key: string): string | undefined {
   const fromProcess = process.env[key]?.trim();
   if (fromProcess) return fromProcess;
+
   return readFromNetlifyEnv(key);
 }