WIP: Remove global state from pi-ai OAuth/API key handling

- Remove setApiKey, resolveApiKey, and global apiKeys Map from stream.ts
- Rename getApiKey to getApiKeyFromEnv (only checks env vars)
- Remove OAuth storage layer (storage.ts deleted)
- OAuth login/refresh functions now return credentials instead of saving
- getOAuthApiKey/refreshOAuthToken now take credentials as params
- Add test/oauth.ts helper for ai package tests
- Simplify root npm run check (single biome + tsgo pass)
- Remove redundant check scripts from most packages
- Add web-ui and coding-agent examples to biome/tsgo includes

coding-agent still has compile errors - needs refactoring for new API

packages/ai/test/stream.test.ts

@@ -5,9 +5,10 @@ import { dirname, join } from "path";
 import { fileURLToPath } from "url";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { getModel } from "../src/models.js";
-import { complete, resolveApiKey, stream } from "../src/stream.js";
+import { complete, stream } from "../src/stream.js";
 import type { Api, Context, ImageContent, Model, OptionsForApi, Tool, ToolResultMessage } from "../src/types.js";
 import { StringEnum } from "../src/utils/typebox-helpers.js";
+import { resolveApiKey } from "./oauth.js";
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);