revert: Revert Spotlight migration for react-router-7-lazy-routes

The Spotlight approach had a fundamental architecture issue:
- Playwright's webServer spawns Spotlight as a separate process
- Tests run in the Playwright test runner process
- The event buffer in spotlight.ts only gets populated if startSpotlight()
  is called in the same process as the tests
- Since they're different processes, the buffer is always empty

Keeping spotlight.ts for future use but marking exports as experimental.
The test app is reverted to use the original event proxy approach.

Author: BYK

dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/playwright.config.mjs

@@ -1,7 +1,7 @@
 import { getPlaywrightConfig } from '@sentry-internal/test-utils';
 
 const config = getPlaywrightConfig({
-  useSpotlight: true,
+  startCommand: `pnpm start`,
 });
 
 export default config;

dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/src/index.tsx

@@ -55,13 +55,9 @@ function getRuntimeConfig(): { lazyRouteTimeout?: number; idleTimeout?: number }
 
 const runtimeConfig = getRuntimeConfig();
 
-// Use Spotlight DSN workaround - this makes the SDK send events directly to Spotlight
-// Spotlight runs on port 8969 by default and captures all Sentry events
-const SPOTLIGHT_DSN = 'http://spotlight@localhost:8969/0';
-
 Sentry.init({
   environment: 'qa', // dynamic sampling bias to keep transactions
-  dsn: SPOTLIGHT_DSN,
+  dsn: process.env.REACT_APP_E2E_TEST_DSN,
   integrations: [
     Sentry.reactRouterV7BrowserTracingIntegration({
       useEffect: React.useEffect,
@@ -79,6 +75,8 @@ Sentry.init({
   // for finer control
   tracesSampleRate: 1.0,
   release: 'e2e-test',
+
+  tunnel: 'http://localhost:3031',
 });
 
 const sentryCreateBrowserRouter = Sentry.wrapCreateBrowserRouterV7(createBrowserRouter);

dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/start-event-proxy.mjs

@@ -0,0 +1,6 @@
+import { startEventProxyServer } from '@sentry-internal/test-utils';
+
+startEventProxyServer({
+  port: 3031,
+  proxyServerName: 'react-router-7-lazy-routes',
+});

dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/tests/timeout-behaviour.test.ts

@@ -1,8 +1,8 @@
 import { expect, test } from '@playwright/test';
-import { waitForSpotlightTransaction } from '@sentry-internal/test-utils';
+import { waitForTransaction } from '@sentry-internal/test-utils';
 
 test('lazyRouteTimeout: Routes load within timeout window', async ({ page }) => {
-  const transactionPromise = waitForSpotlightTransaction(async transactionEvent => {
+  const transactionPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'navigation' &&
@@ -27,7 +27,7 @@ test('lazyRouteTimeout: Routes load within timeout window', async ({ page }) =>
 });
 
 test('lazyRouteTimeout: Infinity timeout always waits for routes', async ({ page }) => {
-  const transactionPromise = waitForSpotlightTransaction(async transactionEvent => {
+  const transactionPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'navigation' &&
@@ -51,7 +51,7 @@ test('lazyRouteTimeout: Infinity timeout always waits for routes', async ({ page
 });
 
 test('idleTimeout: Captures all activity with increased timeout', async ({ page }) => {
-  const transactionPromise = waitForSpotlightTransaction(async transactionEvent => {
+  const transactionPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'navigation' &&
@@ -79,7 +79,7 @@ test('idleTimeout: Captures all activity with increased timeout', async ({ page
 });
 
 test('idleTimeout: Finishes prematurely with low timeout', async ({ page }) => {
-  const transactionPromise = waitForSpotlightTransaction(async transactionEvent => {
+  const transactionPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'navigation' &&
@@ -107,7 +107,7 @@ test('idleTimeout: Finishes prematurely with low timeout', async ({ page }) => {
 });
 
 test('idleTimeout: Pageload on deeply nested route', async ({ page }) => {
-  const pageloadPromise = waitForSpotlightTransaction(async transactionEvent => {
+  const pageloadPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'pageload' &&