[FEATURE] Async agent hooks

[osdemah]

Problem Statement

Currently only blocking functions are supported for agent hooks. This blocks the asyncio event loop and degrades performance for use-cases requiring IO (such as LLM calls in the hooks) for handling of hooks.

Proposed Solution

Support async handlers for hook callbacks. e.g.:

async def my_handler(event: MessageAddedEvent):
    ...
registry.add_callback(MessageAddedEvent, my_handler)

Use Case

IO heavy operations in the callback handlers

Alternatives Solutions

No response

Additional Context

No response