fix(build): make macOS release builds work natively

The --mac-release path (full-node and --lite-backend) had never run on a real
Mac and broke on several Linux-only assumptions:

- build.sh version parser used GNU sed \+ (BSD sed reads it literally), so it
  aborted before compiling — switched to POSIX [[:space:]][[:space:]]*.
- build.sh libsodium universal check used GNU grep \| — switched to grep -E.
- libwebp's cpu.cmake applies -mno-sse2 to its reference DSP files; under a
  universal build (-arch arm64;x86_64) that lands on the x86_64 slice, where it
  disables _Float16 and breaks the SDK 26 <math.h>. Added an idempotent
  FetchContent PATCH_COMMAND (cmake/patch-libwebp-simd.cmake) to neutralize it.
- The SDXL lite backend static lib needs Security + CoreFoundation frameworks on
  macOS; added them to the imported dragonx_lite_backend target for APPLE.
- Added a DRAGONX_MAC_ARCHS override plus auto-detect: with --lite-backend the
  app is built for the arch(es) the backend .a actually provides (its pinned
  ring 0.16.11 is x86_64-only), instead of failing to link a universal app.
- build-lite-backend-artifact.sh uses bash 4+ (mapfile); added a re-exec guard
  for macOS's stock bash 3.2 and added bash to setup.sh's macOS core deps.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

build.sh

@@ -131,7 +131,7 @@ fi
 # truth): the full-node app uses project() VERSION + DRAGONX_VERSION_SUFFIX; ObsidianDragonLite uses
 # DRAGONX_LITE_VERSION + DRAGONX_LITE_VERSION_SUFFIX.
 _cml="$SCRIPT_DIR/CMakeLists.txt"
-_full_ver=$(sed -n 's/^[[:space:]]*VERSION[[:space:]]\+\([0-9][0-9.]*\).*/\1/p' "$_cml" | head -1)
+_full_ver=$(sed -n 's/^[[:space:]]*VERSION[[:space:]][[:space:]]*\([0-9][0-9.]*\).*/\1/p' "$_cml" | head -1)
 _full_suffix=$(sed -n 's/^set(DRAGONX_VERSION_SUFFIX[[:space:]]*"\([^"]*\)").*/\1/p' "$_cml" | head -1)
 _lite_ver=$(sed -n 's/^set(DRAGONX_LITE_VERSION[[:space:]]*"\([^"]*\)").*/\1/p' "$_cml" | head -1)
 _lite_suffix=$(sed -n 's/^set(DRAGONX_LITE_VERSION_SUFFIX[[:space:]]*"\([^"]*\)").*/\1/p' "$_cml" | head -1)
@@ -901,8 +901,26 @@ build_release_mac() {
         fi
         info "macOS cross-compiler: $OSXCROSS_CXX (arch: $MAC_ARCH)"
     else
-        # Native macOS: build universal binary (arm64 + x86_64)
-        MAC_ARCH="universal"
+        # Native macOS: build universal (arm64 + x86_64) by default. Override with
+        # DRAGONX_MAC_ARCHS (e.g. "x86_64").
+        MAC_ARCHS="${DRAGONX_MAC_ARCHS:-arm64;x86_64}"
+        # When linking the real lite backend, the app can only include architectures
+        # the backend static library actually provides. Its pinned ring 0.16.11 has no
+        # Apple-Silicon assembly, so that artifact is x86_64-only — constrain the app
+        # arch to the backend's (unless the user explicitly forced DRAGONX_MAC_ARCHS),
+        # otherwise the arm64 slice fails to link.
+        if $DO_LITE_BACKEND && [[ -z "${DRAGONX_MAC_ARCHS:-}" && -n "${lb_lib:-}" ]] && command -v lipo &>/dev/null; then
+            local _backend_archs; _backend_archs=$(lipo -archs "$lb_lib" 2>/dev/null | tr ' ' ';')
+            if [[ -n "$_backend_archs" && "$_backend_archs" != "$MAC_ARCHS" ]]; then
+                warn "Lite backend provides only [$_backend_archs] — building the app for that instead of universal."
+                MAC_ARCHS="$_backend_archs"
+            fi
+        fi
+        if [[ "$MAC_ARCHS" == *";"* || "$MAC_ARCHS" == *","* ]]; then
+            MAC_ARCH="universal"
+        else
+            MAC_ARCH="$MAC_ARCHS"
+        fi
         export MACOSX_DEPLOYMENT_TARGET="11.0"
     fi
 
@@ -990,7 +1008,7 @@ TOOLCHAIN
             need_sodium=true
         elif [[ -f "$SCRIPT_DIR/libs/libsodium/lib/libsodium.a" ]]; then
             # Rebuild if existing lib is not universal (single-arch won't link)
-            if ! lipo -info "$SCRIPT_DIR/libs/libsodium/lib/libsodium.a" 2>/dev/null | grep -q "arm64.*x86_64\|x86_64.*arm64"; then
+            if ! lipo -info "$SCRIPT_DIR/libs/libsodium/lib/libsodium.a" 2>/dev/null | grep -Eq "arm64.*x86_64|x86_64.*arm64"; then
                 info "Existing libsodium is not universal — rebuilding ..."
                 rm -rf "$SCRIPT_DIR/libs/libsodium"
                 need_sodium=true
@@ -1001,13 +1019,13 @@ TOOLCHAIN
             "$SCRIPT_DIR/scripts/fetch-libsodium.sh"
         fi
 
-        info "Configuring (native universal arm64+x86_64) ..."
+        info "Configuring (native macOS, arch: $MAC_ARCHS) ..."
         cmake "$SCRIPT_DIR" \
             -DCMAKE_BUILD_TYPE=Release \
             -DCMAKE_CXX_FLAGS_RELEASE="-O3 -DNDEBUG" \
             -DDRAGONX_USE_SYSTEM_SDL3=OFF \
             -DCMAKE_OSX_DEPLOYMENT_TARGET=11.0 \
-            -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64" \
+            -DCMAKE_OSX_ARCHITECTURES="$MAC_ARCHS" \
             "${CMAKE_LITE_ARGS[@]}"
     fi