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/src/stream.ts

@@ -18,8 +18,9 @@ import type {
 } from "./types.js";
 
 /**
- * Get API key from environment variables (sync).
- * Does NOT check OAuth credentials - use getApiKeyAsync for that.
+ * Get API key for provider from known environment variables, e.g. OPENAI_API_KEY.
+ *
+ * Will not return API keys for providers that require OAuth tokens.
  */
 export function getApiKeyFromEnv(provider: KnownProvider): string | undefined;
 export function getApiKeyFromEnv(provider: string): string | undefined;