fix(windows): fix numpy DLL loading in embedded Python distribution

- Generate numpy/_distributor_init_local.py during build so libopenblas
  can be located when running from the Windows installer
- Add os.add_dll_directory() call at runtime as a fallback for embedded Python

build-dist-windows.sh

@@ -119,6 +119,22 @@ for whl in "$WHEEL_DIR"/*.whl; do
     unzip -qo "$whl" -d "$SITE_PACKAGES"
 done
 
+# numpy wheels from PyPI don't include _distributor_init_local.py unless
+# patched by delvewheel. In embedded Python, os.add_dll_directory() is never
+# called, so libopenblas can't be found and numpy fails to import.
+# Generate the missing loader here instead.
+if [ -d "${SITE_PACKAGES}/numpy" ]; then
+    cat > "${SITE_PACKAGES}/numpy/_distributor_init_local.py" << 'EOF'
+import os
+import sys
+if sys.platform == 'win32':
+    _libs = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'numpy.libs'))
+    if os.path.isdir(_libs):
+        os.add_dll_directory(_libs)
+EOF
+    echo "Generated numpy/_distributor_init_local.py"
+fi
+
 cleanup_site_packages "$SITE_PACKAGES" "pyd" "dll"
 verify_frontend
 copy_app_files "$DIST_DIR"