[#442] Update frontend for redeployed ZapPlotLinkV2

[realproject7]

Depends on: #442 (contract redeployed with new address)

Summary

After #442 redeploys ZapPlotLinkV2, update the frontend with the new contract address. No logic changes needed in lib/zap.ts — the ABI is the same, only the address changes.

Changes

lib/contracts/constants.ts

• Update ZAP_PLOTLINK mainnet value to the new deployed address from [Contract] Fix ZapPlotLinkV2: HUNT routing via MCV2 bonding curve, not Uniswap #442

Acceptance Criteria

• ZAP_PLOTLINK updated with new mainnet address
• Build passes

Branch

Same PR as #442 contract work, or separate task/442-update-constants