Fix LastRateLimitedBlock in state

The first value in LastRateLimitedBlock is empty, this looks like a broken state. 

1. Write migration to fix it
2. Find the root cause

<img width="1920" height="1359" alt="Image" src="https://github.com/user-attachments/assets/d3461bad-65a3-42e0-8f33-217cd7850871" />