chore(vendor): import pi 0.85.1

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/coding-agent/examples/extensions/widget-placement.ts

@@ -0,0 +1,9 @@
+import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+
+export default function widgetPlacementExtension(pi: ExtensionAPI) {
+	pi.on("session_start", (_event, ctx) => {
+		if (!ctx.hasUI) return;
+		ctx.ui.setWidget("widget-above", ["Above editor widget"]);
+		ctx.ui.setWidget("widget-below", ["Below editor widget"], { placement: "belowEditor" });
+	});
+}