fix: remove duplicate imports, params, and dead code in rewards.ts

[joelpeace48-cell]

Summary

src/lib/api/rewards.ts failed to compile:

• Duplicate PaginatedResponse import (lines 3 and 5)
• getRewardHistory declared two parameters named params, shadowing the first with an unused GetRewardHistoryParams type
• An incomplete apiClient.get call (unclosed paren) followed by a second, complete implementation
• GetRewardHistoryParams was dead — grep confirms the only real caller (src/lib/hooks/use-rewards.ts) uses getRewardHistory(historyParams, jwt, signal) against the RewardHistoryParams interface

Fix: removed the duplicate import, the dead GetRewardHistoryParams interface, the shadowed parameter, and the incomplete code block — keeping the single working implementation that matches the real call site's argument order and the exported RewardHistoryParams type.

Closes #425
Closes #371
Closes #361
Closes #360

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