Homepage “Realtime To-dos” demo intermittently duplicates inserts and inconsistently deletes items

# Bug report ## Describe the bug On the Supabase homepage, the Realtime To-do demo (in the Realtime section) behaves inconsistently. Adding a single todo sometimes creates two identical entries. Deleting multiple items in quick succession sometimes removes only one (or the list briefly de-syncs and reverts). Behaviour is intermittent but frequent enough to reproduce without heroic effort. ## To Reproduce Steps to reproduce the behavior, please provide code snippets or a repository: 1. Go to ['…'](https://supabase.com/realtime) 2. Click on **Todo List** 3. Add a to-do 4. Remove a to-do 5. See error (duplicates) ## Expected behavior Just one to-do should be added, but multiple get added instead. ## Screenshots https://github.com/user-attachments/assets/968d2dee-b351-4923-b2e2-725b2fb7cb87 ## System information - OS: macOS Ventura - Browser Chrome Version 139.0.7258.128 (Official Build) (arm64)