Build a markdown editor called "MarkPad" with split-pane view.
- Left pane: code editor with monospace font and line numbers
- Right pane: rendered preview with full markdown support
- Toolbar: Bold, Italic, Heading, Link, Image, Code, Quote, List, Table
- File operations: New, Download as .md, Copy HTML
- Live preview updates as you type
- Word and character count in status bar
- Resizable split pane divider
- Sample markdown loaded by default showing all features
Design: VS Code-inspired dark editor (#1e1e1e), light preview pane, blue accent (#007acc).