Refactor keybindings with groups and symbols

Introduce a `Group` enum to categorize actions and add `group` and
`symbol`
fields to `KeyBinding`. Extend `Action` with `Up`, `Down`, `Space`, and
`Esc`, updating all keybinding definitions accordingly.

Update `binding_for_view` to return the new actions per view and handle
`Esc` by returning to the main menu.

Rewrite the keybindings widget as a custom `Widget` that renders grouped
paragraphs with proper layout.

Adjust the main menu layout percentages to accommodate the new widget.

src/app/keybindings/keybindings.rs

@@ -4,17 +4,39 @@ use ratatui::crossterm::event::{KeyCode, KeyEvent, KeyEventKind, KeyModifiers};
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Action {
     Quit,
-    ScrollUp,
-    ScrollDown,
+    Up,
+    Down,
+    Space,
+    Esc,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Group {
+    Quit,
+    Movement,
     Select,
 }
 
+impl Group {
+    pub fn iter() -> impl Iterator<Item = Group> {
+        [Group::Quit, Group::Movement, Group::Select]
+            .iter()
+            .copied()
+    }
+
+    pub fn len() -> usize {
+        Self::iter().count()
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct KeyBinding {
     pub action: Action,
     pub code: KeyCode,
     pub kind: KeyEventKind,
     pub modifiers: KeyModifiers,
+    pub group: Group,
+    pub symbol: &'static str,
     pub description: &'static str,
 }
 
@@ -24,29 +46,46 @@ pub static KEYBINDINGS: &[KeyBinding] = &[
         code: KeyCode::Char('q'),
         kind: KeyEventKind::Press,
         modifiers: KeyModifiers::NONE,
+        group: Group::Quit,
+        symbol: "q",
         description: "Quit",
     },
     KeyBinding {
-        action: Action::ScrollUp,
+        action: Action::Up,
         code: KeyCode::Up,
         kind: KeyEventKind::Press,
         modifiers: KeyModifiers::NONE,
+        group: Group::Movement,
+        symbol: "↑",
         description: "Up",
     },
     KeyBinding {
-        action: Action::ScrollDown,
+        action: Action::Down,
         code: KeyCode::Down,
         kind: KeyEventKind::Press,
         modifiers: KeyModifiers::NONE,
+        group: Group::Movement,
+        symbol: "↓",
         description: "Down",
     },
     KeyBinding {
-        action: Action::Select,
+        action: Action::Space,
         code: KeyCode::Char(' '),
         kind: KeyEventKind::Press,
         modifiers: KeyModifiers::NONE,
+        group: Group::Select,
+        symbol: "Space",
         description: "Select",
     },
+    KeyBinding {
+        action: Action::Esc,
+        code: KeyCode::Esc,
+        kind: KeyEventKind::Press,
+        modifiers: KeyModifiers::NONE,
+        group: Group::Movement,
+        symbol: "Esc",
+        description: "Go back",
+    },
 ];
 
 pub fn binding_for(action: Action) -> Option<&'static KeyBinding> {
@@ -63,11 +102,14 @@ pub fn event_to_action(event: &KeyEvent) -> Option<Action> {
 pub fn binding_for_view(view: View) -> Vec<&'static KeyBinding> {
     match view {
         View::MainMenu => vec![
-            binding_for(Action::ScrollUp).unwrap(),
-            binding_for(Action::ScrollDown).unwrap(),
-            binding_for(Action::Select).unwrap(),
+            binding_for(Action::Up).unwrap(),
+            binding_for(Action::Down).unwrap(),
+            binding_for(Action::Space).unwrap(),
             binding_for(Action::Quit).unwrap(),
         ],
-        _ => vec![],
+        _ => vec![
+            binding_for(Action::Quit).unwrap(),
+            binding_for(Action::Esc).unwrap(),
+        ],
     }
 }