fix(claim): checksum SIWE wallet address before signing

[GsCommand]

Motivation

• SIWE message parsing requires the address line to be EIP-55 checksummed and some providers return lowercase addresses, causing malformed_message errors.
• The change focuses on normalizing the wallet address client-side so the SIWE message contains a checksummed address and verification succeeds.

Description

• Added a browser UMD include for ethers to public/claim.html so client code can call ethers.getAddress for checksum normalization.
• Implemented toChecksumAddress(address) that uses ethers.getAddress(...) and surfaces a clear user-visible error when conversion fails.
• Normalized the eth_requestAccounts result to an EIP-55 checksummed address when connecting the wallet and before building the SIWE message in the sign-in flow in public/claim.html.
• Ensured personal_sign is invoked with the same checksummed account and did not change backend SIWE validation behavior.

Testing

• Ran npm install and then repository tests with npm test, where all tests passed (31 tests, 0 failures).
• Ran the example checks in examples/webhook-auto-verify via cd examples/webhook-auto-verify && npm install && npm run check, which completed successfully.
• Attempted npm run build but the repository has no build script (confirmed as missing).

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Codex Task

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Project	Deployment	Actions	Updated (UTC)
commandlayer-commandlayer-org	Ready	Preview, Comment	May 22, 2026 3:32am
commandlayer-org	Ready	Preview, Comment	May 22, 2026 3:32am
commandlayer-org111	Ready	Preview, Comment	May 22, 2026 3:32am