Add minimal GTK4/libadwaita window with header bar and status page

pixstrip-gtk/src/main.rs

@@ -1,3 +1,38 @@
+use adw::prelude::*;
+
+const APP_ID: &str = "live.lashman.Pixstrip";
+
 fn main() {
-    println!("Pixstrip GTK - v{}", pixstrip_core::version());
+    let app = adw::Application::builder()
+        .application_id(APP_ID)
+        .build();
+
+    app.connect_activate(build_ui);
+    app.run();
+}
+
+fn build_ui(app: &adw::Application) {
+    let header = adw::HeaderBar::new();
+
+    let title = adw::WindowTitle::new("Pixstrip", "Batch Image Processor");
+    header.set_title_widget(Some(&title));
+
+    let content = adw::StatusPage::builder()
+        .title("Pixstrip")
+        .description(format!("v{}", pixstrip_core::version()).as_str())
+        .icon_name("image-x-generic-symbolic")
+        .build();
+
+    let toolbar_view = adw::ToolbarView::new();
+    toolbar_view.add_top_bar(&header);
+    toolbar_view.set_content(Some(&content));
+
+    let window = adw::ApplicationWindow::builder()
+        .application(app)
+        .default_width(900)
+        .default_height(650)
+        .content(&toolbar_view)
+        .build();
+
+    window.present();
 }