fix(feedback): check isFinishing/isDestroyed before showing dialog

Add proactive activity validity check inside the runOnUiThread lambda
to avoid hitting the catch block with a BadTokenException when the
activity becomes invalid between the shake callback and UI execution.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonis

sentry-android-core/src/main/java/io/sentry/android/core/FeedbackShakeIntegration.java

@@ -150,7 +150,9 @@ private void startShakeDetection(final @NotNull Activity activity) {
               && !Boolean.TRUE.equals(inBackground)) {
             active.runOnUiThread(
                 () -> {
-                  if (isDialogShowing) {
+                  if (isDialogShowing
+                      || active.isFinishing()
+                      || active.isDestroyed()) {
                     return;
                   }
                   try {