Add XCUI runtime screen layer and demo textarea

Assets/XCUI/NewEditor/Demo/View.xcui

@@ -52,6 +52,19 @@
           value="" />
       </Column>
     </Card>
+    <Card id="notesCard" style="MetricCard">
+      <Column gap="6">
+        <Text text="Session notes" style="MetricLabel" />
+        <TextArea
+          id="sessionNotes"
+          style="CommandArea"
+          width="stretch"
+          min-width="240"
+          rows="4"
+          placeholder="Write multiline notes, prompts, or todos for the current screen..."
+          value="" />
+      </Column>
+    </Card>
     <Button id="toggleAccent" action="demo.toggleAccent" style="AccentButton">
       <Text text="Toggle Accent" style="ButtonLabel" />
     </Button>