Fix iOS Metro reload after initial bundle failure (#58352)

Summary:
If the first bundle request fails on bridgeless iOS, Metro reload does nothing — the app sits on the error screen and has to be killed and relaunched, even once the source is fixed. Android already handles this.

The cause is timing. `RCTInstance` resolves the `DevSettings` TurboModule only inside `_loadJSBundle`'s success callback, and `RCTDevSettings.initialize` is what registers the Metro `reload` message handler. No successful first load means no handler, so the app never becomes a Metro reload peer.

This resolves `DevSettings` at the top of `_loadJSBundle`, before the request is issued, so the handler is registered regardless of how that request turns out. The callback keeps its own resolution for the HMR setup that follows it.

## Changelog:

[IOS] [FIXED] - Allow Metro reload after an initial bundle-load failure.

Pull Request resolved: #58352

Test Plan:
On RNTester (iOS 26.5 simulator), launched with an unresolved import so the initial bundle fails, then restored the source and waited 10 seconds: the error stayed and Metro received no bundle request, confirming the app was not a reload peer. Sending `{version: 2, method: "reload"}` to Metro then made it request a corrected bundle and recover in place, native PID `95823` unchanged. A second consecutive reload also worked.

Same scenario on Android RNTester as the reference: it already receives the Metro command on the initial-error path, recovering with PID `14848` unchanged.

Reviewed By: christophpurrer

Differential Revision: D119072108

Pulled By: javache

fbshipit-source-id: 8774564b990417cc143f55ba935b809f50eff485

Author: janicduplessis

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTInstance.mm

@@ -537,6 +537,10 @@ - (void)handleBundleLoadingError:(NSError *)error
 
 - (void)_loadJSBundle:(NSURL *)sourceURL
 {
+  // DevSettings is needed by _loadScriptFromSource's callback, so it must be initialized first. Doing it before
+  // the request, not after a successful load, also lets Metro reload when the initial bundle request fails.
+  [_turboModuleManager moduleForName:"DevSettings"];
+
 #if RCT_DEV_MENU && __has_include(<React/RCTDevLoadingViewProtocol.h>)
   {
     id<RCTDevLoadingViewProtocol> loadingView =
@@ -569,7 +573,6 @@ - (void)_loadJSBundle:(NSURL *)sourceURL
           [strongSelf handleBundleLoadingError:error];
           return;
         }
-        // DevSettings module is needed by _loadScriptFromSource's callback so prior initialization is required
         RCTDevSettings *const devSettings =
             (RCTDevSettings *)[strongSelf->_turboModuleManager moduleForName:"DevSettings"];
         [strongSelf _loadScriptFromSource:source];