fix: clean up stale miner data when hotkey re-links to new GitHub account

[tmimmanuel]

Summary

• Existing cleanup only handled one direction: same github_id re-registering on a new (uid, hotkey)
• Missing the reverse: same (uid, hotkey) linking to a new github_id — old GitHub's rows were never deleted
• This caused duplicate entries (e.g. madelyngamble2) showing stale data with same $/day but 0 score
• Added three reverse cleanup queries (CLEANUP_STALE_*_BY_HOTKEY) and call them in cleanup_stale_miner_data()

Scenario

1. User registers madelyngamble2, links wallet, gets hotkey
2. User stops mining with madelyngamble2
3. User registers spider-yamet with the same wallet/hotkey
4. Old entry for madelyngamble2 is never cleaned up → duplicate in UI

Related entrius/gittensor-ui#124

[anderdc]

just merged big changes into test please fix conflicts thanks

[tmimmanuel]

@anderdc I resolved merge conflicts, plz review.