Enhance ESLint configuration and chat components

Enhance citation handling and UI components

Enhance reasoning delta handling and chat message preview

Enhance chat message formatting and tool input serialization

Enhance AGENTS.md with conventions for frontend text and data ownership

Refactor chat-message component to support activity blocks

bugfix thinking pill was growing when results came in

Fix reasoning font

Add Next.js frontend with chat functionality, including components for chat messages, source panels, and markdown rendering. Update README with setup instructions and enhance .gitignore for frontend build artifacts.