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/examples/tui/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "example-tui"
+edition = "2024"
+version.workspace = true
+readme.workspace = true
+license.workspace = true
+publish = false
+
+[dependencies]
+harmony = { path = "../../harmony" }
+harmony_tui = { path = "../../harmony_tui" }
+harmony_types = { path = "../../harmony_types" }
+cidr = { workspace = true }
+tokio = { workspace = true }
+harmony_macros = { path = "../../harmony_macros" }
+log = { workspace = true }
+env_logger = { workspace = true }
+url = { workspace = true }