Fix Chrome Custom Tab race condition causing window not to close after verification

[seftena]

Problem

After verification completes, the Chrome Custom Tab was not dismissing
automatically on Android. Stephen Hagans at CVS reported this as an
ongoing issue after the previous fix.

Root Cause

IDmeRedirectActivity.handleIntent() was reading callingActivity after
calling handleRedirect(). handleRedirect() completes the deferred, which
allows the launchAuth coroutine to immediately resume on Dispatchers.IO
and null out callingActivity in its finally block — before the main
thread could read it. The window-close intent was silently dropped 100%
of the time under this ordering.

Fix

Capture IDmeAuthManager.callingActivity?.get() into a local variable
before handleRedirect() is called. The local variable is immune to
concurrent modification by the IO thread.

Files Changed

• sdk/src/main/kotlin/com/idme/auth/auth/IDmeRedirectActivity.kt