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/modes/index.ts

@@ -0,0 +1,16 @@
+/**
+ * Run modes for the coding agent.
+ */
+
+export { InteractiveMode, type InteractiveModeOptions } from "./interactive/interactive-mode.ts";
+export type { JsonAgentSessionEvent } from "./json-event.ts";
+export { type PrintModeOptions, runPrintMode } from "./print-mode.ts";
+export { type ModelInfo, RpcClient, type RpcClientOptions, type RpcEventListener } from "./rpc/rpc-client.ts";
+export { runRpcMode } from "./rpc/rpc-mode.ts";
+export type {
+	RpcCommand,
+	RpcExtensionUIRequest,
+	RpcExtensionUIResponse,
+	RpcResponse,
+	RpcSessionState,
+} from "./rpc/rpc-types.ts";