fix(app): unsubscribe ReactionController on modal close

Addresses a regression where the video modal close action (back button) could leave active subscriptions or state. This change ensures `ReactionController.unsubscribe()` is called within `hideModal()`.

js/app.js

@@ -394,6 +394,9 @@ class Application {
     if (this.videoModal) {
       this.videoModal.close();
     }
+    if (this.reactionController) {
+      this.reactionController.unsubscribe();
+    }
     // Also clear the active modal state if tracked elsewhere, though videoModal.close() usually handles it.
   }