Deduplicate Registered Voters View

[atomauro]

Summary

The "Hasn't voted" list contained duplicate entries for certain users (e.g., betaalpha.near). This was traced back to the registered_voters view returning multiple rows for a single user due to multiple deploy_lockup events not being filtered correctly.

Changes

• Modified registered_voters.sql to use ROW_NUMBER() OVER (PARTITION BY registered_voter_id ...) logic.
• This ensures we strictly select only the first valid registration event per user, eliminating duplicates at the source without the performance cost of a global DISTINCT.