fix(ai): revert selective pi-ai base entrypoints

packages/ai/test/openai-completions-tool-choice.test.ts

@@ -1,8 +1,8 @@
 import { Type } from "typebox";
 import { beforeEach, describe, expect, it, vi } from "vitest";
-import { stream, streamSimple } from "../src/index.ts";
 import { getModel } from "../src/models.ts";
 import { convertMessages } from "../src/providers/openai-completions.ts";
+import { stream, streamSimple } from "../src/stream.ts";
 import type { AssistantMessage, Model, SimpleStreamOptions, Tool, ToolResultMessage } from "../src/types.ts";
 
 const mockState = vi.hoisted(() => ({