Refactor view handling and keybinding API

Move the `View` enum to a dedicated module and implement `Widget` for
`&App` there.
Rename `default_view_keybindings` to `default_keybindings` and adjust
its
signature. Redesign `KeybindingsWidget` to accept an explicit list of
bindings instead of a `View`. Update imports, function signatures, and
rendering
logic across the codebase to reflect these changes.

src/app/mod.rs

@@ -2,11 +2,13 @@ pub mod app;
 pub mod game_states;
 pub mod keybind;
 pub mod keybindings;
-pub mod widget;
+pub mod view;
+pub mod views;
 pub mod widgets;
 
-pub use app::{App, Event, GameMode, PerkDecks, View, handle_input_events};
+pub use app::{App, Event, GameMode, PerkDecks, handle_input_events};
 pub use game_states::{
     GameStates, MainMenuState, PerkDecksState, SettingsState, SkillsConfigState, SkirmishState,
 };
 pub use keybind::handle_keybindings;
+pub use view::View;