fix(ios): resolve hermesc for SwiftPM apps in react-native-xcode.sh

Release bundling derived hermesc exclusively from $PODS_ROOT/hermes-engine,
which does not exist in a SwiftPM app — every SwiftPM consumer's Release
build depended on HERMES_CLI_PATH being set by hand (or on the injector's
baked path never going stale). When no Pods installation exists and the
current HERMES_CLI_PATH does not point at a real file, resolve the
hermes-compiler npm package through react-native's own dependency graph:
react-native pins hermes-compiler, so the compiler's bytecode version always
matches the prebuilt hermes VM artifacts. The missing-file condition also
heals injector-baked paths gone stale after a package-store move.

Strictly SwiftPM-scoped: in a CocoaPods build the hermes-engine pod owns
both the VM and hermesc, and its hermes train may legitimately differ from
the npm package — an ungated fallback compiled bundles the podded VM
rejected at launch ("Wrong bytecode version"), which is why the no-Pods
gate is load-bearing.

Shell-only change with no unit harness; verified end-to-end by the local
iOS build matrix: spm Release cells green on monorepo and fresh-consumer
apps via the fallback, all CocoaPods cells green with the fallback provably
inert.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: chrfalch

packages/react-native/scripts/react-native-xcode.sh

@@ -80,6 +80,26 @@ source "$REACT_NATIVE_DIR/scripts/node-binary.sh"
 HERMES_ENGINE_PATH="$PODS_ROOT/hermes-engine"
 [ -z "$HERMES_CLI_PATH" ] && HERMES_CLI_PATH="$HERMES_ENGINE_PATH/destroot/bin/hermesc"
 
+# SwiftPM consumers have no Pods directory to provide hermesc. When there is
+# no Pods installation at all and the current HERMES_CLI_PATH does not exist
+# (unset, or an injector-baked path gone stale after a package-store move),
+# resolve the hermes-compiler npm package THROUGH react-native's own dependency
+# graph — react-native pins the hermes-compiler version, so the compiler's
+# bytecode version always matches the prebuilt hermes VM artifacts (a
+# mismatched pair crashes at launch with "Wrong bytecode version").
+# STRICTLY SwiftPM-scoped: in a CocoaPods build the hermes-engine pod owns both
+# the VM and hermesc, and its hermes train may legitimately differ from the npm
+# hermes-compiler — falling back there would compile bundles the podded VM
+# rejects.
+if [[ ( -z "$PODS_ROOT" || ! -d "$PODS_ROOT" ) && ! -f "$HERMES_CLI_PATH" ]]; then
+  NODE_HERMESC=$(RN_DIR="$REACT_NATIVE_DIR" "$NODE_BINARY" --print \
+    "require('path').join(require('path').dirname(require.resolve('hermes-compiler/package.json', {paths: [process.env.RN_DIR]})), 'hermesc', 'osx-bin', 'hermesc')" \
+    2>/dev/null || true)
+  if [[ -n "$NODE_HERMESC" && -f "$NODE_HERMESC" ]]; then
+    HERMES_CLI_PATH="$NODE_HERMESC"
+  fi
+fi
+
 # If hermesc is not available and USE_HERMES is not set to false, show error.
 if [[ $USE_HERMES != false && -f "$HERMES_ENGINE_PATH" && ! -f "$HERMES_CLI_PATH" ]]; then
   echo "error: Hermes is enabled but the hermesc binary could not be found at ${HERMES_CLI_PATH}." \