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/protocol/src/index.ts

@@ -0,0 +1,22 @@
+export * from "./cbor/index.ts";
+export * from "./codec.ts";
+export * from "./framing.ts";
+export {
+	type AttachmentEnvelope,
+	type CancelEnvelope,
+	type ClientHello,
+	type ClientMessage,
+	isServerId,
+	PROTOCOL_VERSION,
+	type ProtocolError,
+	type ProtocolErrorCode,
+	type RequestEnvelope,
+	type ResponseEnvelope,
+	type RpcTarget,
+	type ServerHello,
+	type ServerHelloError,
+	type ServerId,
+	type ServerMessage,
+	type ServiceEventEnvelope,
+	type SessionTarget,
+} from "./protocol.ts";