[#432] Zap v2 Frontend Lib: Rewrite lib/zap.ts + update constants

[realproject7]

Parent: #432

Depends on: #433 (need deployed contract address)

Summary

Rewrite lib/zap.ts to match the new multi-token ZapPlotLink v2 contract interface. Update lib/contracts/constants.ts with mainnet addresses.

lib/contracts/constants.ts

• Update ZAP_PLOTLINK mainnet value with deployed address from [#432] Zap v2 Contract: Re-fork with multi-token support + mainnet deploy #433
• Add supported input token addresses on Base mainnet:
  • USDC: Base mainnet USDC address
  • HUNT: Base mainnet HUNT address
• Export a SUPPORTED_ZAP_TOKENS list for the frontend selector

lib/zap.ts

Rewrite to match new contract interface with fromToken parameter:

• getZapQuote(fromToken, storylineToken, amount, mode: 'exact-output' | 'exact-input') — calls estimateMint / estimateMintReverse via simulateContract (non-view functions)
• buildZapMintTx(fromToken, storylineToken, amount, mode, ...):
  • ETH (address(0)): payable with msg.value, no approval needed
  • ERC-20 (USDC/HUNT): requires prior approval to Zap contract
• Apply slippage buffer (0.5% for swap, 3% for bonding curve)
• Remove Uniswap V4 Quoter calls — the contract's estimateMint/estimateMintReverse handle the full path estimation

Acceptance Criteria

• lib/zap.ts compiles cleanly
• Constants updated with mainnet Zap address
• USDC and HUNT addresses added
• Quote functions work for all 3 input tokens (ETH, USDC, HUNT)
• Build passes (npm run build)

Branch

task/432-zap-v2-frontend in plotlink repo

[realproject7]

Frontend lib rewritten for ZapPlotLinkV2. PR #436 merged.