feat: implement main application structure with UI and layout management

- Added main application logic in `src/ui/app.rs` to handle state and modal dialogs.
- Created module structure for UI components in `src/ui/mod.rs`.
- Implemented column configuration screen in `src/ui/screens/configuracao_colunas.rs`.
- Developed file import screen in `src/ui/screens/import.rs` for CSV and XLSX files.
- Added layout management screen in `src/ui/screens/layouts.rs` for saving and importing layouts.
- Created result display screen in `src/ui/screens/resultado.rs` to show analysis results.
- Introduced modular organization for screens in `src/ui/screens/mod.rs`.

src/main.rs

@@ -1,3 +1,26 @@
-fn main() {
-    println!("Hello, world!");
+mod application;
+mod domain;
+mod infrastructure;
+mod ui;
+
+use ui::app::App;
+
+fn main() -> eframe::Result {
+    let native_options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default()
+            .with_title("Comparador de Notas")
+            .with_inner_size([1024.0, 768.0])
+            .with_min_inner_size([800.0, 600.0]),
+        ..Default::default()
+    };
+
+    eframe::run_native(
+        "Comparador de Notas",
+        native_options,
+        Box::new(|_cc| {
+            let mut app = App::default();
+            app.inicializar();
+            Ok(Box::new(app))
+        }),
+    )
 }