Description

This PR introduces an asynchronous context manager (action) to the Messages mixin, allowing users to continuously broadcast a chat action (e.g., typing, uploading) without manually managing the loop.

It creates a background task that resends the action every delay seconds and automatically sends enums.ChatAction.CANCEL upon exiting the context block.

Example usage:

import asyncio
from hydrogram import enums

async with app.action(chat_id, enums.ChatAction.TYPING):
    await asyncio.sleep(10)
    await app.send_message(chat_id, "Done!")

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

Manually tested by running a bot and invoking the context manager with a 10-second sleep to verify the typing indicator remains active beyond the standard 5-second Telegram limit, and disappears exactly after the block exits.

• Tested enums.ChatAction.TYPING with asyncio.sleep
• Verified enums.ChatAction.CANCEL is properly dispatched on __aexit__

Test Configuration

• Operating System: macOS
• Python Version: 3.14

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes