fix: resolve viewport undefined error in custom scripts

Fixes FORMBRICKS-NG

The issue was caused by importing and re-exporting the viewport constant
from a shared module in the survey layout file. This re-export pattern
could cause bundling issues where the viewport variable name leaked into
the global scope or interfered with custom scripts.

Changes:
- Define viewport export directly in app/s/[surveyId]/layout.tsx
- Remove viewport export from modules/survey/link/layout.tsx to prevent
  scope pollution
- This ensures viewport metadata stays scoped to Next.js and doesn't
  conflict with custom scripts that may define their own viewport variables

apps/web/app/s/[surveyId]/layout.tsx

@@ -1,5 +1,12 @@
-import { LinkSurveyLayout, viewport } from "@/modules/survey/link/layout";
+import { Viewport } from "next";
+import { LinkSurveyLayout } from "@/modules/survey/link/layout";
 
-export { viewport };
+export const viewport: Viewport = {
+  width: "device-width",
+  initialScale: 1.0,
+  maximumScale: 1.0,
+  userScalable: false,
+  viewportFit: "contain",
+};
 
 export default LinkSurveyLayout;

apps/web/modules/survey/link/layout.tsx

@@ -1,13 +1,3 @@
-import { Viewport } from "next";
-
-export const viewport: Viewport = {
-  width: "device-width",
-  initialScale: 1.0,
-  maximumScale: 1.0,
-  userScalable: false,
-  viewportFit: "contain",
-};
-
 export const LinkSurveyLayout = ({ children }) => {
   return <div className="h-dvh">{children}</div>;
 };