feat: add verbose mode to Agent (#800)

.changeset/rude-ducks-invent.md

examples/.env.example

examples/agent/openai.ts

packages/core/src/Settings.ts

packages/core/src/agent/anthropic.ts

packages/core/src/agent/base.ts

packages/core/src/agent/openai.ts

packages/core/src/agent/react.ts

packages/core/src/agent/types.ts

packages/core/src/agent/utils.ts

packages/core/src/engines/chat/types.ts

packages/core/src/internal/logger.ts