fix: reset StartupLogger on JS reload so runJsBundleStart marker is recorded (#56339)

PR #54255 (which made StartupLogger reset on APP_STARTUP_START) introduced a regression in 0.83 where the `runJsBundleStart` performance marker is dropped on JS reload. On reload, RUN_JS_BUNDLE_START and INIT_REACT_RUNTIME_START fire and are rejected by the still-populated StartupLogger as duplicates; only afterward does APP_STARTUP_START fire and reset the logger, leaving NaN start times paired with valid end times. As a result `performance.measure('runJsBundle', 'runJsBundleStart', 'runJsBundleEnd')` throws "The mark 'runJsBundleStart' does not exist." after the first load.

Pre-emptively call StartupLogger::reset() at the top of ReactInstance::loadScript so every load (including reloads) starts with a clean logger and the startup markers are recorded correctly each time.

Author: mohanrajvenkatesan23-04

packages/react-native/ReactCommon/react/runtime/ReactInstance.cpp

@@ -248,6 +248,12 @@ void ReactInstance::loadScript(
       beforeLoad(runtime);
     }
     TraceSection s("ReactInstance::loadScript");
+    // Reset the StartupLogger so that JS reloads re-record all START/STOP
+    // timings. Without this, the APP_STARTUP_START handler resets the logger
+    // mid-sequence (after RUN_JS_BUNDLE_START / INIT_REACT_RUNTIME_START have
+    // already been rejected as duplicates), leaving NaN start times paired
+    // with valid end times. See issue #56339.
+    ReactMarker::StartupLogger::getInstance().reset();
     bool hasLogger(ReactMarker::logTaggedMarkerBridgelessImpl != nullptr);
     if (hasLogger) {
       ReactMarker::logTaggedMarkerBridgeless(