feat(notch): add shared NotchPill container

src/window/panel/notch/pill.py

@@ -0,0 +1,41 @@
+from fabric.widgets.box import Box
+from fabric.widgets.centerbox import CenterBox
+from fabric.widgets.shapes import Corner
+
+
+class NotchPill(Box):
+    def __init__(self, center_widget, v_align="center", **kwargs):
+        super().__init__(
+            name="panel-notch-wrap",
+            orientation="h",
+            spacing=0,
+            v_align=v_align,
+            h_align="center",
+            h_expand=False,
+            **kwargs,
+        )
+        self.left_corner = Corner(
+            name="panel-notch-corner",
+            orientation="top-right",
+            size=20,
+            h_align="start",
+            v_align="start",
+        )
+        self.right_corner = Corner(
+            name="panel-notch-corner",
+            orientation="top-left",
+            size=20,
+            h_align="end",
+            v_align="start",
+        )
+        self.center_widget = center_widget
+        self.notch_box = CenterBox(
+            name="panel-notch",
+            orientation="h",
+            h_align="center",
+            v_align="center",
+            start_children=self.left_corner,
+            center_children=center_widget,
+            end_children=self.right_corner,
+        )
+        self.add(self.notch_box)