feat(hemieth): add contract deployment config for Hemi L2

[nvrakesh06]

Summary

• Adds contract deployment configuration for Hemi L2 (mainnet and testnet)
• Adds HEMIETH (chain ID 43111) and HEMIETH_TESTNET (chain ID 743111) to config/chainIds.ts
• Adds hemieth and themieth network entries to hardhat.config.ts
• Adds Hemi explorer API key and custom chain entries for contract verification
• Adds HEMIETH / HEMIETH_TESTNET cases to scripts/chainConfig.ts using ForwarderV4 / ForwarderFactoryV4

Jira

• CECHO-598 (Hemi contract deployment config)
• CECHO-115 (Hemi L2 sandboxing task)

Test plan

• Verify HEMIETH and HEMIETH_TESTNET chain IDs are correct (43111 / 743111)
• Run deployment script against themieth testnet to confirm contracts deploy successfully
• Verify contract verification works with Hemi explorer API

🤖 Generated with Claude Code

[nvrakesh06]

{
  "walletImplementation": "0xC5F797551F0Cb16294CF01bc12654bA845f83487",
  "walletFactory": "0xBCe7Aa7F5504A70aa2D1D2eebEA8d9ED6ffA053F",
  "forwarderImplementation": "0xdE5ccBAF38427035b1Df40AC38E3E00AF92c49CB",
  "forwarderFactory": "0xd0fa83f0515651F4104d42f2f014f134DfFf93d4"
}

[nayandas190]

lgtm