fix: Newline renders as yoga carrier (text node) when standalone

Match Ink's behavior where Newline renders as ink-text (yoga carrier).
When inside a Text parent, Newline still renders as virtual-text for
inline behavior. When standalone, it renders as a text node so it
participates in yoga layout and occupies vertical space.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/runtime/src/components/Newline.ts

@@ -1,9 +1,28 @@
-import { defineComponent, h } from "vue";
+import { defineComponent, getCurrentInstance, h } from "vue";
 
 export const Newline = defineComponent({
   name: "Newline",
   props: { count: { type: Number, default: 1 } },
   setup(props) {
-    return () => h("virtual-text", {}, "\n".repeat(props.count));
+    return () => {
+      const content = "\n".repeat(props.count);
+      // Inside a Text parent, render as inline virtual-text.
+      // Outside Text, render as "text" (yoga carrier) so Newline participates
+      // in layout standalone, matching Ink's ink-text behavior.
+      if (isInsideText()) {
+        return h("virtual-text", {}, content);
+      }
+      return h("text", {}, content);
+    };
   },
 });
+
+function isInsideText(): boolean {
+  let parent = getCurrentInstance()?.parent;
+  while (parent) {
+    const name = parent.type && (parent.type as { name?: string }).name;
+    if (name === "Text") return true;
+    parent = parent.parent;
+  }
+  return false;
+}