Gate LiveActivity 300ms delay on RSC_SUSPENSE_DEMO_DELAY

The setTimeout was firing on every request, including production
deployments — verified via curl on the review-app: /rsc_payload/
LiveActivity took ~1000ms vs ~620ms for /rsc_payload/ServerComponentsPage
across 3 trials, ~400ms gap matching the unconditional 300ms delay.

Same opt-in gate as CommentsFeed: enabled when env var is exactly 'true',
off by default. Review-app keeps the visible behavior because app.yml
sets RSC_SUSPENSE_DEMO_DELAY=true.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ihabadham

client/app/bundles/server-components/ror_components/LiveActivity.jsx

@@ -6,10 +6,13 @@ async function LiveActivity({ simulateError = false }) {
     throw new Error('Simulated server-side render failure (demo)');
   }
 
-  // Small delay so the refresh-in-flight state is visible.
-  await new Promise((resolve) => {
-    setTimeout(resolve, 300);
-  });
+  // Opt-in delay so the refresh-in-flight state is visible in the demo.
+  // Matches the gate in CommentsFeed; off by default in production.
+  if (process.env.RSC_SUSPENSE_DEMO_DELAY === 'true') {
+    await new Promise((resolve) => {
+      setTimeout(resolve, 300);
+    });
+  }
 
   const stats = {
     serverTime: new Date().toISOString(),