Implement ScoreListWidget to manage score list rendering and execution confirmation flow. This includes methods for scrolling through scores, launching an execution, confirming/denying the execution, and rendering a popup for user confirmation.
Add a new `harmony_tui` crate to initialize and run a text-based user interface (TUI) for the Harmony project using `ratatui` for rendering and `crossterm` for handling input. The `HarmonyTUI` struct initializes the terminal, enters a loop to render updates, and handles basic input events to exit. This commit sets up the foundation for further TUI development.
