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/empty.test.ts

@@ -1,7 +1,8 @@
 import { describe, expect, it } from "vitest";
 import { getModel } from "../src/models.js";
-import { complete, resolveApiKey } from "../src/stream.js";
+import { complete } from "../src/stream.js";
 import type { Api, AssistantMessage, Context, Model, OptionsForApi, UserMessage } from "../src/types.js";
+import { resolveApiKey } from "./oauth.js";
 
 // Resolve OAuth tokens at module level (async, runs before tests)
 const oauthTokens = await Promise.all([