Refactor the whole structure, no more separation for C++ and Slint files

src/windows/AppWindow/AppWindow.slint

@@ -0,0 +1,26 @@
+import { AppWindowModels } from "Models.slint";
+import { Button, VerticalBox, CheckBox } from "std-widgets.slint";
+import { SideBar } from "views/SideBar.slint";
+import { MainView } from "views/TasksView.slint";
+import { SettingsWindow } from "../SettingsWindow/SettingsWindow.slint";
+import { AddSourceWindow } from "../AddSourceWindow//AddSourceWindow.slint";
+import { EditSourceWindow } from "../EditSourceWindow/EditSourceWindow.slint";
+import { Palette } from "@selenite";
+
+export component AppWindow inherits Window {
+
+	title: "Mirai";
+	min-height: 100px;
+	max-height: 4000px; // needed, otherwise the window wants to fit the content (on Swaywm)
+	default-font-size: 16px;
+
+    HorizontalLayout {
+		SideBar {}
+		MainView {
+			horizontal-stretch: 1;
+		}
+     }
+	
+}
+
+export { AppWindowModels, Palette, SettingsWindow, AddSourceWindow, EditSourceWindow } // Export to make it visible to the C++ backend