fix: use -fmodule-map-file for Swift metadata discovery in nsld.sh (#374)

Replace HEADER_SEARCH_PATHS-based module discovery with explicit
-fmodule-map-file= for the nsswiftsupport modulemap. The directory-based
discovery via -I was unreliable — the metadata generator's clang would
sometimes fail to find the modulemap, or during parallel multi-arch
builds, discover modulemaps from both architectures through the parent
internal/ directory (which is also in HEADER_SEARCH_PATHS), causing
"redefinition of module 'nsswiftsupport'" errors and potentially using a
stale bridging header from the wrong architecture.

This resulted in intermittent "ReferenceError: <class> is not defined"
errors for Swift plugin classes after npm install, requiring a full
platforms/ delete to recover.

Author: edusperoni

project-template-ios/internal/nsld.sh

@@ -62,7 +62,7 @@ function GEN_METADATA() {
 }
 
 GEN_MODULEMAP $TARGET_ARCH
-export HEADER_SEARCH_PATHS="$HEADER_SEARCH_PATHS \"$MODULES_DIR\""
+export OTHER_CFLAGS="$OTHER_CFLAGS -fmodule-map-file=\"$MODULES_DIR/module.modulemap\""
 printf "Generating metadata..."
 GEN_METADATA $TARGET_ARCH
 DELETE_SWIFT_MODULES_DIR

project-template-vision/internal/nsld.sh

@@ -62,7 +62,7 @@ function GEN_METADATA() {
 }
 
 GEN_MODULEMAP $TARGET_ARCH
-export HEADER_SEARCH_PATHS="${HEADER_SEARCH_PATHS:+$HEADER_SEARCH_PATHS }\"$MODULES_DIR\""
+export OTHER_CFLAGS="${OTHER_CFLAGS:+$OTHER_CFLAGS }-fmodule-map-file=\"$MODULES_DIR/module.modulemap\""
 printf "Generating metadata..."
 GEN_METADATA $TARGET_ARCH
 DELETE_SWIFT_MODULES_DIR