feat(MOB): WebView 핀치 줌 기능 추가

- setSupportZoom(true) 설정
- setBuiltInZoomControls(true) 설정
- setDisplayZoomControls(false) 줌 버튼 UI 숨김

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

android/app/src/main/java/com/codebridgex/webapp/MainActivity.java

@@ -24,6 +24,11 @@ public class MainActivity extends BridgeActivity {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         createNotificationChannels();
+
+        // WebView 줌 설정 (핀치 줌 활성화)
+        getBridge().getWebView().getSettings().setSupportZoom(true);
+        getBridge().getWebView().getSettings().setBuiltInZoomControls(true);
+        getBridge().getWebView().getSettings().setDisplayZoomControls(false);
     }
 
     private void createNotificationChannels() {