#3757 feat(web): add AI section to homepage

Summary

• Adds a "Build with any AI tool" section to the homepage, right after "Style with any tools", showing Claude Code, Codex, Cursor, Copilot, v0 and Lovable.
• Shows the official skill install command (npx skills add resend/react-email) with copy-to-clipboard, plus a link to the LLM docs (/docs/llms.txt).
• Adds a short "Using with AI" section to the README with the same command and link.

Tiles reuse the Primitives section styling. Claude and Cursor logos come from their official brand assets; Codex, Copilot, v0 and Lovable come from @lobehub/icons.

Test plan

• Homepage renders the new section after "Style with any tools" on desktop and mobile (3-column grid on small screens)
• Copy button copies npx skills add resend/react-email
• "Docs for LLMs" opens /docs/llms.txt
• README renders correctly on GitHub

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Summary by cubic

Adds a "Build with any AI" section to the homepage and a matching "Using with AI" section to the README, with spacing adjustments to the adjoining Testimonial section.

• Tiles for Claude Code, Codex, Cursor, Copilot, v0, and Lovable copy an agent-specific install prompt and show "Copied" feedback; clipboard errors are silently ignored.
• Tiles have a cursor-tracking highlight and lift on hover.
• The section provides the npx skills add resend/react-email command and a link to /docs/llms.txt; the README section includes the same command and link.