Agent-HTML swaps Markdown for interactive artifacts

Markdown is great for human-to-AI instructions, but it's a poor choice for AI-to-human complex technical delivery.

• –Replaces ephemeral chat streams with stable `.agent.html` files that support interactive SVG diagrams and functional UI components.
• –Uses a strict semantic schema that acts as a public contract, preventing agents from "hallucinating" broken CSS or non-standard HTML.
• –Artifacts are portable and single-file, ensuring long-term readability without external dependencies or heavy frameworks.
• –Integrates directly as a "skill" for agents like Claude Code, allowing them to output structured reports, architecture maps, and prototypes.
• –The shift from text-only logs to "interactive artifacts" is a critical step toward making AI agents feel like professional-grade engineering tools.