Add react-markdown + remark-math + rehype-katex to render the AI's
markdown (headings, bold, lists, code, blockquotes, tables) and LaTeX
math ($H_2O$ etc.). ReactMarkdown escapes raw HTML, keeping the stored
message rendering safe from XSS. Styled via .markdown-body in Message.css.
Applied to assistant messages only; user text stays plain.
- Add TopNav component with AI Chat, Study Guides, Progress tabs
- Refactor sidebar to include brand, new chat, subjects, chat history, settings
- Add message action buttons (Helpful, Note, Deeper) on assistant responses
- Enhance ChatInput with photo, mic attachment icons and AI disclaimer
- Improve welcome state with 2x2 suggested prompt grid
- Update global layout for proper sidebar offset (fix nav overlap)
- Remove obsolete Header component
- All styles: strict BEM naming, zero inline CSS, Paper Look theme
hahachait