feat(city): app loop, terminal guard, save format, gen CLI

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/city/src/term.rs

@@ -0,0 +1,40 @@
+//! Raw-mode terminal setup that always restores the shell, even on panic.
+
+use anyhow::Result;
+use crossterm::{cursor, execute, terminal};
+use ratatui::Terminal;
+use ratatui::backend::CrosstermBackend;
+use std::io::{Stdout, stdout};
+
+/// Restores the terminal when dropped.
+pub struct TerminalGuard;
+
+impl TerminalGuard {
+    pub fn enter() -> Result<(Self, Terminal<CrosstermBackend<Stdout>>)> {
+        terminal::enable_raw_mode()?;
+        execute!(stdout(), terminal::EnterAlternateScreen, cursor::Hide)?;
+        let term = Terminal::new(CrosstermBackend::new(stdout()))?;
+        Ok((TerminalGuard, term))
+    }
+}
+
+impl Drop for TerminalGuard {
+    fn drop(&mut self) {
+        restore();
+    }
+}
+
+/// Leaves raw mode and the alternate screen. Safe to call more than once.
+pub fn restore() {
+    let _ = terminal::disable_raw_mode();
+    let _ = execute!(stdout(), terminal::LeaveAlternateScreen, cursor::Show);
+}
+
+/// Makes a panic restore the terminal before printing its message.
+pub fn install_panic_hook() {
+    let previous = std::panic::take_hook();
+    std::panic::set_hook(Box::new(move |info| {
+        restore();
+        previous(info);
+    }));
+}