fix(ios): Guard replay postInit behind runtime session replay check (#5858)

* fix(ios): Guard replay postInit behind runtime session replay check

When iOS deployment target >= 16.0, SENTRY_TARGET_REPLAY_SUPPORTED is
true at compile time, but postInit was called unconditionally even when
session replay was not configured. This caused a SIGABRT crash on launch
in release builds with New Architecture (TurboModules) because the
breadcrumb converter installed by postInit referenced a nil replay
instance.

Fixes #5679

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(ios): Add changelog entry for replay postInit guard

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Fixes lint issue

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonis

CHANGELOG.md

@@ -10,6 +10,7 @@
 
 ### Fixes
 
+- Fix SIGABRT crash on launch when `mobileReplayIntegration` is not configured and iOS deployment target >= 16.0 ([#5858](https://github.com/getsentry/sentry-react-native/pull/5858))
 - Reduce `reactNavigationIntegration` performance overhead ([#5840](https://github.com/getsentry/sentry-react-native/pull/5840), [#5842](https://github.com/getsentry/sentry-react-native/pull/5842), [#5849](https://github.com/getsentry/sentry-react-native/pull/5849))
 - Fix duplicated breadcrumbs on Android ([#5841](https://github.com/getsentry/sentry-react-native/pull/5841))
 

packages/core/ios/RNSentryStart.m

@@ -29,7 +29,10 @@ + (void)startWithOptions:(SentryOptions *)options NS_SWIFT_NAME(start(options:))
     [SentrySDK startWithOptions:options];
 
 #if SENTRY_TARGET_REPLAY_SUPPORTED
-    [RNSentryReplay postInit];
+    if (options.sessionReplay.sessionSampleRate > 0
+        || options.sessionReplay.onErrorSampleRate > 0) {
+        [RNSentryReplay postInit];
+    }
 #endif
 
     [self postDidBecomeActiveNotification];