bug: RLN fails to reset at epoch limit

[darshankabariya]

RLN allows up to 100 messages per epoch (10 minutes), but a potential bug causes message limits to carry over into the next epoch.

Steps to Reproduce:

1. Assume an epoch starts at 4:00.
2. Do not send any messages between 4:00 and 4:06.
3. Send 100 messages between 4:06 and 4:09.
4. At the start of the new epoch (4:10), attempts to send more messages result in a "message limit exceeded" error.
5. You can only send messages again at 4:16, after 6 minutes into the new epoch.

Expected Behavior:
The message limit should reset at the start of a new epoch (e.g., 4:10), allowing up to 100 new messages regardless of prior activity.

Observed Behavior:
If 100 messages are sent late in an epoch (e.g., 4:06-4:09), the limit does not reset at the start of the next epoch (4:10). Instead, the "message limit exceeded" error persists until several minutes into the new epoch.

Note:
This issue was observed while using the chat interface (REST API), suggesting it might be a bug in the API implementation.