feat(tanstackstart-react): Add E2E test for tunnel route

Add tunnel route and E2E test to verify createSentryTunnelRoute functionality.
The test ensures the tunnel endpoint returns 200 and correctly forwards envelopes.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: cursoragent

dev-packages/e2e-tests/test-applications/tanstackstart-react/src/routes/api.tunnel.ts

@@ -0,0 +1,8 @@
+import{createFileRoute}from'@tanstack/react-router';
+import{createSentryTunnelRoute}from'@sentry/tanstackstart-react';
+
+exportconstRoute=createFileRoute('/api/tunnel')({
+server: createSentryTunnelRoute({
+allowedDsns: [process.env.E2E_TEST_DSN||''],
+}),
+});

dev-packages/e2e-tests/test-applications/tanstackstart-react/tests/tunnel.test.ts

@@ -0,0 +1,66 @@
+import{expect,test}from'@playwright/test';
+import{waitForError}from'@sentry-internal/test-utils';
+
+test('Tunnel route forwards envelopes to Sentry',async({ baseURL })=>{
+consterrorEventPromise=waitForError('tanstackstart-react',errorEvent=>{
+returnerrorEvent?.exception?.values?.[0]?.value==='Test error for tunnel route';
+});
+
+constdsn=process.env.E2E_TEST_DSN||'';
+const[protocol,rest]=dsn.split('://');
+const[auth,hostAndPath]=rest.split('@');
+const[publicKey]=auth.split(':');
+const[host, ...pathParts]=hostAndPath.split('/');
+constprojectId=pathParts[pathParts.length-1];
+
+constenvelope=[
+JSON.stringify({event_id: crypto.randomUUID(),sent_at: newDate().toISOString()}),
+JSON.stringify({
+type: 'event',
+length: 0,
+}),
+JSON.stringify({
+exception: {
+values: [
+{
+type: 'Error',
+value: 'Test error for tunnel route',
+},
+],
+},
+platform: 'javascript',
+sdk: {
+name: 'sentry.javascript.tanstackstart-react',
+version: '0.0.0',
+},
+timestamp: Date.now()/1000,
+}),
+].join('\n');
+
+consttunnelUrl=`${baseURL}/api/tunnel`;
+constsentryUrl=`${protocol}://${host}/api/${projectId}/envelope/`;
+
+constresponse=awaitfetch(tunnelUrl,{
+method: 'POST',
+headers: {
+'Content-Type': 'application/x-sentry-envelope',
+'X-Sentry-Auth': `Sentry sentry_key=${publicKey}, sentry_version=7`,
+},
+body: `${sentryUrl}\n${envelope}`,
+});
+
+expect(response.status).toBe(200);
+
+consterrorEvent=awaiterrorEventPromise;
+
+expect(errorEvent).toMatchObject({
+exception: {
+values: [
+{
+type: 'Error',
+value: 'Test error for tunnel route',
+},
+],
+},
+});
+});