[codex] polish homepage byline credits

[pandazki]

Summary

• Polish the homepage footer byline into a compact attribution block.
• Add localized design labels: design for English and 设计 for Chinese.
• Add local Claude and Codex icon assets and show them alongside designer avatars.
• Adjust footer grid and byline styling so attribution stays compact on wide screens and wraps cleanly below the breakpoint.

Validation

• npm run build

Notes

• Rebased onto the latest upstream main before opening this PR.