feat(tui): ratatui skeleton with layout

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

crates/tui/src/app.rs

@@ -0,0 +1,17 @@
+pub struct App {
+    pub should_quit: bool,
+}
+
+impl App {
+    pub fn new() -> Self {
+        Self { should_quit: false }
+    }
+
+    pub fn handle_key(&mut self, key: crossterm::event::KeyEvent) {
+        match key.code {
+            crossterm::event::KeyCode::Char('q') => self.should_quit = true,
+            crossterm::event::KeyCode::Esc => self.should_quit = true,
+            _ => {}
+        }
+    }
+}

crates/tui/src/main.rs

@@ -1 +1,41 @@
-fn main() {}
+use clap::Parser;
+
+mod app;
+mod ui;
+
+#[derive(Parser)]
+#[command(name = "log-viewer", about = "A log viewer TUI")]
+struct Cli {
+    /// Log files to open
+    files: Vec<String>,
+}
+
+fn main() -> anyhow::Result<()> {
+    let _cli = Cli::parse();
+
+    crossterm::terminal::enable_raw_mode()?;
+    let mut stdout = std::io::stdout();
+    crossterm::execute!(stdout, crossterm::terminal::EnterAlternateScreen)?;
+    let backend = ratatui::backend::CrosstermBackend::new(stdout);
+    let mut terminal = ratatui::Terminal::new(backend)?;
+
+    let mut app = app::App::new();
+
+    while !app.should_quit {
+        terminal.draw(|frame| ui::render(frame, &app))?;
+        if crossterm::event::poll(std::time::Duration::from_millis(100))?
+            && let crossterm::event::Event::Key(key) = crossterm::event::read()?
+        {
+            app.handle_key(key);
+        }
+    }
+
+    crossterm::terminal::disable_raw_mode()?;
+    crossterm::execute!(
+        terminal.backend_mut(),
+        crossterm::terminal::LeaveAlternateScreen
+    )?;
+    terminal.show_cursor()?;
+
+    Ok(())
+}

crates/tui/src/ui.rs

@@ -0,0 +1,26 @@
+use crate::app::App;
+
+pub fn render(frame: &mut ratatui::Frame, _app: &App) {
+    use ratatui::layout::{Constraint, Layout};
+    use ratatui::widgets::{Block, Borders, Paragraph};
+
+    let chunks = Layout::vertical([
+        Constraint::Length(1),
+        Constraint::Min(1),
+        Constraint::Length(1),
+    ])
+    .split(frame.area());
+
+    frame.render_widget(
+        Paragraph::new(" Log Viewer").style(ratatui::style::Style::default().bold()),
+        chunks[0],
+    );
+
+    // Main area — 使用 Block::new()（ratatui 0.30 推荐风格）
+    frame.render_widget(
+        Block::new().borders(Borders::ALL).title("No file loaded"),
+        chunks[1],
+    );
+
+    frame.render_widget(Paragraph::new(" Press '?' for help | q to quit"), chunks[2]);
+}