feat(splashscreen): enhance startup sequence and splashscreen handling

This update improves the splashscreen management during application startup. The splashscreen will now remain visible for a minimum duration and will only close after the main application is ready, ensuring a smoother user experience.

- Introduced a new startup sequence to manage background tasks.
- Added error handling for splashscreen closure to maintain functionality.
- Optimized the timing for displaying and hiding the splashscreen.

src-tauri/src/main.rs

@@ -22,14 +22,22 @@ use git::{
 use tauri::Manager;
 
 #[tauri::command]
-fn close_splashscreen(app: tauri::AppHandle) {
+fn close_splashscreen(app: tauri::AppHandle) -> Result<(), String> {
+    if let Some(window) = app.get_webview_window("splashscreen") {
+        let _ = window.hide();
+        window
+            .destroy()
+            .map_err(|error| format!("failed to destroy splashscreen: {error}"))?;
+    }
+
     if let Some(window) = app.get_webview_window("main") {
-        let _ = window.show();
+        window
+            .show()
+            .map_err(|error| format!("failed to show main window: {error}"))?;
         let _ = window.set_focus();
     }
-    if let Some(window) = app.get_webview_window("splashscreen") {
-        let _ = window.close();
-    }
+
+    Ok(())
 }
 
 #[tokio::main]