fix: remove NavView fragment via the FragmentManager it is attached to

NavViewManager.onDropViewInstance removed the map/navigation fragment
through reactContext.getCurrentActivity()'s support FragmentManager.
When the view is dropped while getCurrentActivity() points at a
different Activity than the one hosting the fragment (e.g. after
Activity recreation), that FragmentManager never hosted the fragment
and androidx throws:

  IllegalStateException: Cannot remove Fragment attached to a different
  FragmentManager

Use the fragment's own getParentFragmentManager() for the remove
transaction instead, and guard against the FragmentManager being
already destroyed mid-teardown. This also no longer skips cleanup
(leaking the fragmentMap entry) when getCurrentActivity() is null.

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

Author: christian-apollo

android/src/main/java/com/google/android/react/navsdk/NavViewManager.java

@@ -304,18 +304,24 @@ public void onDropViewInstance(@NonNull FrameLayout view) {
       controllerSink.clear();
     }
 
-    FragmentActivity activity = (FragmentActivity) reactContext.getCurrentActivity();
-    if (activity == null) return;
-
     WeakReference<IMapViewFragment> weakReference = fragmentMap.remove(viewId);
     if (weakReference != null) {
       IMapViewFragment fragment = weakReference.get();
       if (fragment != null && fragment.isAdded()) {
-        activity
-            .getSupportFragmentManager()
-            .beginTransaction()
-            .remove((Fragment) fragment)
-            .commitNowAllowingStateLoss();
+        // Remove via the FragmentManager the fragment is actually attached to.
+        // reactContext.getCurrentActivity() can be a different Activity than the one hosting the
+        // fragment (e.g. after Activity recreation), in which case removing through its
+        // FragmentManager throws "Cannot remove Fragment attached to a different FragmentManager".
+        try {
+          ((Fragment) fragment)
+              .getParentFragmentManager()
+              .beginTransaction()
+              .remove((Fragment) fragment)
+              .commitNowAllowingStateLoss();
+        } catch (IllegalStateException e) {
+          // FragmentManager already destroyed mid-teardown; the fragment is torn down with its
+          // host Activity anyway.
+        }
       }
     }
   }