fix(build): pin the native SwiftPM build system for the computer-use universal binary (#21146)

SwiftPM 6.4 (Xcode 27) defaults to the swiftbuild build system, which writes
products to an xcodebuild-style layout instead of .build/<triple>/release, so
the lipo step in build-computer-macos.mjs finds no inputs. Pass
--build-system native to both per-triple builds.

Fixes #21145

config/scripts/build-computer-macos.mjs

@@ -29,7 +29,18 @@ createHelperApp()
 
 function buildUniversalBinary() {
   const builtBinaries = universalTriples.map((triple) => {
-    run('swift', ['build', '-c', 'release', '--package-path', packagePath, '--triple', triple])
+    // SwiftPM 6.4+ swiftbuild default skips the .build/<triple>/release layout lipo reads (#21145)
+    run('swift', [
+      'build',
+      '-c',
+      'release',
+      '--package-path',
+      packagePath,
+      '--triple',
+      triple,
+      '--build-system',
+      'native'
+    ])
     return path.join(packagePath, '.build', triple, 'release', 'orca-computer-use-macos')
   })
   mkdirSync(path.dirname(binaryPath), { recursive: true })