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/proxy/package.json

@@ -11,7 +11,6 @@
 	"scripts": {
 		"clean": "rm -rf dist",
 		"build": "tsc",
-		"check": "biome check --write .",
 		"typecheck": "tsgo --noEmit",
 		"dev": "tsx src/cors-proxy.ts 3001"
 	},