Improve Windows stash behaviour (#2543)

* Rename manager.instance to Manager
* Show dialog message on fatal error on Windows
* Hide console windows explicitly on icon launch

Gets rid of the windowsgui flag, which causes all sorts of issues.
Instead, checks if stash was launched from the icon, and if so hides the console.

* Remove fixconsole
* Add changelog entries

internal/api/server.go

@@ -41,7 +41,7 @@ var githash string
 var uiBox = ui.UIBox
 var loginUIBox = ui.LoginUIBox
 
-func Start() {
+func Start() error {
 	initialiseImages()
 
 	r := chi.NewRouter()
@@ -263,16 +263,18 @@ func Start() {
 		displayAddress = "http://" + displayAddress + "/"
 	}
 
-	go func() {
-		if tlsConfig != nil {
-			logger.Infof("stash is running at " + displayAddress)
-			logger.Error(server.ListenAndServeTLS("", ""))
-		} else {
-			logger.Infof("stash is running at " + displayAddress)
-			logger.Error(server.ListenAndServe())
-		}
-		manager.GetInstance().Shutdown(0)
-	}()
+	logger.Infof("stash is running at " + displayAddress)
+	if tlsConfig != nil {
+		err = server.ListenAndServeTLS("", "")
+	} else {
+		err = server.ListenAndServe()
+	}
+
+	if !errors.Is(err, http.ErrServerClosed) {
+		return err
+	}
+
+	return nil
 }
 
 func printVersion() {