Fix all clippy lints and pass CI checks

- Box large enum variants in EventData to reduce memory footprint
- Add Default trait implementations for types with new() methods
- Replace or_insert_with(Vec::new) with or_default()
- Convert vec init+push patterns to vec! macro
- Fix field reassignment with default initialization
- Convert match to if for simple equality checks
- Remove unused Backend type parameters from TUI draw functions
- Apply rustfmt formatting

All tests passing (24 total). Zero clippy warnings. Ready for CI/CD.

ghost-tui/src/main.rs

@@ -69,7 +69,7 @@ async fn run_app<B: Backend>(terminal: &mut Terminal<B>, app: Arc<Mutex<App>>) -
         // Draw the UI
         terminal.draw(|f| {
             if let Ok(app) = app.try_lock() {
-                ui::draw::<CrosstermBackend<std::io::Stdout>>(f, &app);
+                ui::draw(f, &app);
             }
         })?;