added pair screen, home screen, and channels screen

desktop_app/ui/widgets/home_sidebar.py

@@ -0,0 +1,39 @@
+from textual.containers import Vertical
+from textual.widgets import Button, ContentSwitcher
+
+
+class SidebarButton(Button):
+    DEFAULT_CSS = """
+    SidebarButton {
+        max-width: 100%;
+        margin-bottom: 1;
+    }
+    """
+
+class HomeSidebar(Vertical):
+    DEFAULT_CSS = """
+    HomeSidebar {
+        width: 11;
+        background: $boost;
+        border-right: $surface-lighten-1 tall;
+        padding: 1;
+        dock: left;
+        margin-top: 1;
+    }
+    """
+    
+    def on_button_pressed(self, event: Button.Pressed):
+        content_switcher: ContentSwitcher = self.screen.query_one(ContentSwitcher)
+        
+        match event.button.id:
+            case "home-btn":
+                content_switcher.current = "home-info"
+            case "channels-btn":
+                content_switcher.current = "channels-list"
+            case "settings-btn":
+                content_switcher.current = "settings"
+    
+    def compose(self):
+        yield SidebarButton("", tooltip="Home", id="home-btn")
+        yield SidebarButton("", tooltip="Channels", id="channels-btn")
+        yield SidebarButton("", tooltip="Settings", id="settings-btn")