Add tests, fix offset logic, and bump dependencies

- Introduce a comprehensive test suite (cli, app, board, tasks, audio)
  and a
  new TESTING.md document describing test execution.
- Correct vertical offset calculation in `BoardState` to use saturating
  subtraction and ceiling division.
- Clamp initial `Offset` values to the provided maximum in
  `Offset::new`.
- Export `load_audio` from the audio thread module and switch to
  `LoopedDecoder` for proper OGG looping.
- Update several crate versions: clap, ratatui, log, rodio, and
  bitflags.

tests/app.rs

@@ -0,0 +1,161 @@
+use clap::Parser;
+use ratatui::{
+    Terminal,
+    backend::TestBackend,
+    crossterm::event::{KeyCode, KeyEvent, KeyEventKind, KeyModifiers},
+    layout::Rect,
+};
+use std::sync::mpsc::{Receiver, channel};
+use war_in_tunnels::{
+    app::{App, GameStates, View, handle_keybindings, threads::AudioCmd},
+    cli::Cli,
+};
+
+fn app() -> (App, Receiver<AudioCmd>) {
+    let args = Cli::try_parse_from(["game", "--disable-audio"]).unwrap();
+    let (tx, rx) = channel();
+    let mut app = App::new(args, tx);
+    app.window_area = Rect::new(0, 0, 120, 40);
+    app.states = Some(GameStates::new(&app.args, &app.window_area));
+    (app, rx)
+}
+
+fn press(app: &mut App, code: KeyCode) {
+    handle_keybindings(app, KeyEvent::new(code, KeyModifiers::NONE));
+}
+
+#[test]
+fn menu_selection_stays_in_bounds_and_opens_each_view() {
+    let (mut app, _) = app();
+    for _ in 0..10 {
+        press(&mut app, KeyCode::Up);
+    }
+    assert_eq!(app.states_ref().unwrap().main_menu.selected_view, 1);
+    for view in [View::Skirmish, View::PerkDecks, View::SkillsConfig] {
+        press(&mut app, KeyCode::Char(' '));
+        assert_eq!(app.view, view);
+        press(&mut app, KeyCode::Esc);
+        assert_eq!(app.view, View::MainMenu);
+        press(&mut app, KeyCode::Down);
+    }
+    for _ in 0..10 {
+        press(&mut app, KeyCode::Down);
+    }
+    assert_eq!(app.states_ref().unwrap().main_menu.selected_view, 3);
+}
+
+#[test]
+fn quit_keys_work_in_every_view() {
+    for view in [
+        View::MainMenu,
+        View::Skirmish,
+        View::PerkDecks,
+        View::SkillsConfig,
+    ] {
+        for key in [
+            KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE),
+            KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+        ] {
+            let (mut app, _) = app();
+            app.view = view;
+            handle_keybindings(&mut app, key);
+            assert!(app.exit);
+        }
+    }
+}
+
+#[test]
+fn key_release_does_not_trigger_quit() {
+    let (mut app, _) = app();
+    handle_keybindings(
+        &mut app,
+        KeyEvent::new_with_kind(
+            KeyCode::Char('q'),
+            KeyModifiers::NONE,
+            KeyEventKind::Release,
+        ),
+    );
+    assert!(!app.exit);
+}
+
+#[test]
+fn music_keys_send_commands_without_opening_audio_device() {
+    let (mut app, rx) = app();
+    press(&mut app, KeyCode::Char('m'));
+    press(&mut app, KeyCode::Char('b'));
+    press(&mut app, KeyCode::Char('n'));
+    assert!(matches!(rx.try_recv().unwrap(), AudioCmd::Mute));
+    assert!(matches!(rx.try_recv().unwrap(), AudioCmd::VolumeUp));
+    assert!(matches!(rx.try_recv().unwrap(), AudioCmd::VolumeDown));
+    drop(rx);
+    press(&mut app, KeyCode::Char('m'));
+    assert!(!app.exit);
+}
+
+#[test]
+fn skirmish_keys_move_focus_toggle_panel_and_limit_zoom() {
+    let (mut app, _) = app();
+    app.view = View::Skirmish;
+    press(&mut app, KeyCode::Right);
+    assert_eq!(
+        app.states_ref()
+            .unwrap()
+            .skirmish
+            .board
+            .get_focused_cell()
+            .get_coords(),
+        (5, 4)
+    );
+    press(&mut app, KeyCode::Tab);
+    assert!(app.states_ref().unwrap().skirmish.side_panel);
+    press(&mut app, KeyCode::Tab);
+    assert!(!app.states_ref().unwrap().skirmish.side_panel);
+    for _ in 0..4 {
+        press(&mut app, KeyCode::Char(','));
+    }
+    assert_eq!(
+        app.states_ref().unwrap().skirmish.board.zoom_level,
+        war_in_tunnels::app::states::skirmish_states::ZoomLevel::ZoomedIn
+    );
+    for _ in 0..4 {
+        press(&mut app, KeyCode::Char('.'));
+    }
+    assert_eq!(
+        app.states_ref().unwrap().skirmish.board.zoom_level,
+        war_in_tunnels::app::states::skirmish_states::ZoomLevel::ZoomedOut
+    );
+}
+
+#[test]
+fn all_views_render_without_real_terminal() {
+    let (mut app, _) = app();
+    let mut terminal = Terminal::new(TestBackend::new(120, 40)).unwrap();
+    for view in [
+        View::MainMenu,
+        View::Skirmish,
+        View::PerkDecks,
+        View::SkillsConfig,
+    ] {
+        app.view = view;
+        let before = app.states.clone();
+        terminal
+            .draw(|frame| frame.render_widget(&mut app, frame.area()))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        let text: String = buffer.content.iter().map(|cell| cell.symbol()).collect();
+        assert!(!text.trim().is_empty(), "{view:?}");
+        if matches!(view, View::PerkDecks | View::SkillsConfig) {
+            assert!(text.contains("Work in progress"));
+        }
+        assert_eq!(app.states, before);
+    }
+}
+
+#[test]
+fn common_keys_work_before_states_are_initialized() {
+    let (mut app, _) = app();
+    app.states = None;
+    press(&mut app, KeyCode::Down);
+    press(&mut app, KeyCode::Char('q'));
+    assert!(app.exit);
+}