feat: add ScoreListWidget with execution confirmation

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.

harmony-rs/harmony_tui/src/widget/ratatui_utils.rs

@@ -0,0 +1,22 @@
+use ratatui::layout::{Constraint, Flex, Layout, Rect};
+
+/// Centers a [`Rect`] within another [`Rect`] using the provided [`Constraint`]s.
+///
+/// # Examples
+///
+/// ```rust
+/// use ratatui::layout::{Constraint, Rect};
+///
+/// let area = Rect::new(0, 0, 100, 100);
+/// let horizontal = Constraint::Percentage(20);
+/// let vertical = Constraint::Percentage(30);
+///
+/// let centered = center(area, horizontal, vertical);
+/// ```
+pub(crate) fn center(area: Rect, horizontal: Constraint, vertical: Constraint) -> Rect {
+    let [area] = Layout::horizontal([horizontal])
+        .flex(Flex::Center)
+        .areas(area);
+    let [area] = Layout::vertical([vertical]).flex(Flex::Center).areas(area);
+    area
+}