test(startup): isolate Windows focusability transition (#37)

- Issue #37: keep the failing startup path hidden and focused-out while removing the post-Ready focusability transition.\n- Use the packaged workflow to distinguish native focusability from other startup causes.\n\nRefs #37.

src-tauri/src/lib.rs

@@ -3996,9 +3996,6 @@ fn mark_main_window_startup_complete(app_handle: &tauri::AppHandle) {
 #[cfg(target_os = "windows")]
 fn reveal_main_window(app_handle: &tauri::AppHandle) {
     if let Some(window) = app_handle.get_webview_window("main") {
-        if let Err(error) = window.set_focusable(true) {
-            log::warn!("Could not make the main window focusable: {error}");
-        }
         if let Err(error) = window.show() {
             eprintln!("Failed to reveal the main window: {error}");
         }
@@ -18558,8 +18555,7 @@ pub fn run() {
                 // re-enter that handler during native construction.
                 main_window_builder = main_window_builder
                     .visible(false)
-                    .focused(false)
-                    .focusable(false);
+                    .focused(false);
             }
             main_window_builder
                 .build()