place_market_order is not a coroutine but examples imply await usage

[ghettof]

Bug Description

The place_market_order method returns an ExecuteResponse object directly
and cannot be used with await. However, since the overall SDK pattern
uses async/await, new users naturally attempt to await this method,
which causes a runtime error.

Steps to Reproduce

# This raises: "object ExecuteResponse can't be used in 'await' expression"
result = await client.market.place_market_order(params=params)

# Correct usage (not documented):
result = client.market.place_market_order(params=params)

Expected Behavior

The docstring should explicitly state:
"This method is synchronous and should NOT be awaited."

Or alternatively, make the method a proper coroutine for consistency
with the rest of the async SDK pattern.

Environment

• nado-protocol SDK version: latest
• Python 3.11