feat: add sync and async sandbox SDK

[KAJdev]

This brings sandbox support to the Python SDK, with a regular Sandbox API and an async AsyncioSandbox API. Both share the same lifecycle and execution logic.

use a context manager for a short-lived sandbox:

from runpod import Sandbox

with Sandbox(image_name="python:3.12-slim") as sandbox:
    result = sandbox.exec(["python", "-c", "print('hello from the sandbox')"], check=True)
    print(result.output)

The async version works the same way:

import asyncio
from runpod import AsyncioSandbox

async def main():
    async with AsyncioSandbox(image_name="python:3.12-slim") as sandbox:
        result = await sandbox.exec(["python", "-c", "print('hello')"], check=True)
        print(result.output)

asyncio.run(main())

To work with a sandbox that's already running, use get(sandbox_id) or list(...). Those handles only close their local connections when you leave the context. they don't terminate the sandbox. You can call terminate() explicitly when you're finished with it.

exec() returns command output, and check=True raises on command failure while keeping any partial output. logs() streams container or system logs and supports resuming with an event's id through last_event_id. Use a context manager around the log stream too if you might stop reading early.

While working on this, I discovered an edge case in log streaming on host that should be addressed as well: CON-1557 / runpod/host#2820.

Linear: CON-1523, CON-1524, CON-1525, CON-1526