Drop crossterm delete App add CLI defaults

Remove the crossterm dependency and its input handling, delete the
now‑unused
App module, and provide default values for all command‑line options.

src/app/widgets/main_menu.rs

@@ -0,0 +1,47 @@
+use ratatui::{
+    buffer::Buffer,
+    layout::{Alignment, Constraint, Layout, Rect},
+    style::{Color, Stylize},
+    text::Line,
+    widgets::{Block, Borders, Paragraph, Widget},
+};
+
+pub fn main_menu_widget(area: Rect, buf: &mut Buffer) {
+    let vertical_layout: Layout =
+        Layout::vertical([Constraint::Percentage(90), Constraint::Percentage(10)]);
+
+    let [main_menu_area, keybindings_area] = vertical_layout.areas(area);
+
+    let title_text: String = vec![
+        r" __    __             _         _____                        _     ",
+        r"/ / /\ \ \__ _ _ __  (_)_ __   /__   \_   _ _ __  _ __   ___| |___",
+        r"\ \/  \/ / _` | '__| | | '_ \    / /\/ | | | '_ \| '_ \ / _ \ / __|",
+        r" \  /\  / (_| | |    | | | | |  / /  | |_| | | | | | | |  __/ \__ \",
+        r"  \/  \/ \__,_|_|    |_|_| |_|  \/    \__,_|_| |_|_| |_|\___|_|___/",
+    ]
+    .join("\n");
+
+    let title: Paragraph<'_> = Paragraph::new(title_text)
+        .alignment(Alignment::Center)
+        .style(Color::Yellow)
+        .block(
+            Block::default()
+                .borders(Borders::LEFT | Borders::RIGHT | Borders::TOP)
+                .style(Color::Gray),
+        );
+
+    title.render(main_menu_area, buf);
+
+    let keybindings_text: Vec<Line<'_>> =
+        vec![Line::from_iter(["q".bold().red(), "\t - Quit".into()])];
+
+    let keybindings: Paragraph<'_> = Paragraph::new(keybindings_text)
+        .alignment(Alignment::Left)
+        .block(
+            Block::default()
+                .borders(Borders::ALL)
+                .title("[ Keybinding ]"),
+        );
+
+    keybindings.render(keybindings_area, buf);
+}

src/app/widgets/mod.rs

@@ -0,0 +1,3 @@
+pub mod main_menu;
+
+pub use main_menu::main_menu_widget;