refactor(ci): Set NEXT_PUBLIC_SENTRY_SPOTLIGHT via real env var instead of next.config.js

This is more realistic - testing the actual env var flow that users would use.
The env var is now conditionally set in CI only for test apps that contain
'spotlight' in their name.

Author: BYK

.github/workflows/build.yml

@@ -991,6 +991,10 @@ jobs:
         run: yarn ci:copy-to-temp ./test-applications/${{ matrix.test-application }} ${{ runner.temp }}/test-application
         working-directory: dev-packages/e2e-tests
 
+      - name: Set Spotlight env var for spotlight tests
+        if: contains(matrix.test-application, 'spotlight')
+        run: echo "NEXT_PUBLIC_SENTRY_SPOTLIGHT=true" >> $GITHUB_ENV
+
       - name: Build E2E app
         working-directory: ${{ runner.temp }}/test-application
         timeout-minutes: 7
@@ -1119,6 +1123,10 @@ jobs:
         run: yarn ci:copy-to-temp ./test-applications/${{ matrix.test-application }} ${{ runner.temp }}/test-application
         working-directory: dev-packages/e2e-tests
 
+      - name: Set Spotlight env var for spotlight tests
+        if: contains(matrix.test-application, 'spotlight')
+        run: echo "NEXT_PUBLIC_SENTRY_SPOTLIGHT=true" >> $GITHUB_ENV
+
       - name: Build E2E app
         working-directory: ${{ runner.temp }}/test-application
         timeout-minutes: 7

dev-packages/e2e-tests/test-applications/nextjs-15-spotlight/next.config.js

@@ -2,11 +2,8 @@ const { withSentryConfig } = require('@sentry/nextjs');
 
 /** @type {import('next').NextConfig} */
 const nextConfig = {
-  // Environment variables for Spotlight testing
-  // NEXT_PUBLIC_* vars are embedded in the client bundle
-  env: {
-    NEXT_PUBLIC_SENTRY_SPOTLIGHT: 'true',
-  },
+  // NEXT_PUBLIC_SENTRY_SPOTLIGHT is set via environment variable in CI
+  // The SDK reads it from process.env during withSentryConfig()
 };
 
 module.exports = withSentryConfig(nextConfig, {