feat(examples/tui): add TUI example with harmony integration

- Create `Cargo.toml` for the new TUI example under `examples/tui`
- Implement basic `main.rs` that initializes Maestro and launches the TUI
- Update `harmony_tui/src/lib.rs` to handle async score execution gracefully

harmony-rs/harmony_tui/src/lib.rs

@@ -61,7 +61,7 @@ enum HarmonyTuiEvent {
 impl HarmonyTUI {
     pub fn new(maestro: Maestro) -> Self {
         let maestro = Arc::new(maestro);
-        let (handle, sender) = Self::start_channel(maestro.clone());
+        let (_handle, sender) = Self::start_channel(maestro.clone());
         let score = ScoreListWidget::new(Self::scores_list(&maestro), sender);
 
         HarmonyTUI {
@@ -83,14 +83,17 @@ impl HarmonyTUI {
                     HarmonyTuiEvent::LaunchScore(score_item) => {
                         let maestro = maestro.clone();
 
-                        let interpretation_result =
+                        let joinhandle_result =
                             tokio::spawn(async move { maestro.interpret(score_item.0).await })
                                 .await;
 
-                        match interpretation_result {
-                            Ok(success) => info!("Score execution successful {success:?}"),
-                            Err(e) => {
-                                error!("Score execution failed {:#?}", e);
+                        match joinhandle_result {
+                            Ok(interpretation_result) => match interpretation_result {
+                                Ok(success) => info!("Score execution successful {success:?}"),
+                                Err(error) => error!("Score failed {error:?}"),
+                            },
+                            Err(joinhandle_failure) => {
+                                error!("Score execution TASK FAILED! {:#?}", joinhandle_failure);
                             }
                         }
                     }