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/src/experimental/cli.ts

@@ -0,0 +1,12 @@
+#!/usr/bin/env node
+import { setupCli } from "../cli/setup.ts";
+import { main } from "../main.ts";
+import { runExperimentalCommand } from "./commands.ts";
+
+setupCli();
+const args = process.argv.slice(2);
+if (await runExperimentalCommand(args)) {
+	if (args[0] === "client") process.exit(process.exitCode ?? 0);
+} else {
+	await main(args);
+}