LOC-7291: download darwin-arm64 binary on Apple Silicon

On macOS the binding now selects BrowserStackLocal-darwin-arm64 when
the runtime reports arm64/aarch64; x64 runtimes (including
x64-under-Rosetta) keep BrowserStackLocal-darwin-x64, preserving
current behavior.

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

Author: vivianludrick

src/main/java/com/browserstack/local/LocalBinary.java

@@ -76,7 +76,12 @@ private void initialize() throws LocalException {
         if (isOSWindows) {
             binFileName = "BrowserStackLocal.exe";
         } else if (osname.contains("mac") || osname.contains("darwin")) {
-            binFileName = "BrowserStackLocal-darwin-x64";
+            String arch = System.getProperty("os.arch");
+            if (arch.contains("aarch64") || arch.contains("arm64")) {
+                binFileName = "BrowserStackLocal-darwin-arm64";
+            } else {
+                binFileName = "BrowserStackLocal-darwin-x64";
+            }
         } else if (osname.contains("linux")) {
             String arch = System.getProperty("os.arch");
             if (arch.contains("aarch64")) {