Pro UI Mode & Rich Chat

A major visual upgrade to the entire app. Chat messages now render rich formatting -- headers, bold, code blocks with syntax highlighting, tables, and more. Loading states are smoother, components are more polished, and keyboard accessibility is improved across the board.

• ›Rich markdown rendering in chat -- headers, bold, italic, lists, tables, and blockquotes display beautifully
• ›Syntax-highlighted code blocks with one-click copy buttons
• ›Smooth skeleton loading animations replace plain "Loading..." text across all pages
• ›New Pro/Classic UI toggle in Settings -- switch back to the original look anytime
• ›Improved keyboard navigation with visible focus indicators
• ›Toast notifications now work for copy, save, and error feedback
• ›Enhanced button, input, card, and badge components with proper loading, disabled, and error states