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

tsconfig.json

@@ -27,5 +27,6 @@
 			"@mariozechner/pi-agent-old/*": ["./packages/agent-old/src/*"]
 		}
 	},
-	"include": ["packages/*/src/**/*", "packages/*/test/**/*", "packages/coding-agent/examples/**/*"]
+	"include": ["packages/*/src/**/*", "packages/*/test/**/*", "packages/coding-agent/examples/**/*"],
+	"exclude": ["packages/web-ui/**/*"]
 }