Fix Python streaming examples in docs

[sztoplover-bit]

Summary

• fix the Python streaming examples in the root README and Python README
• update the quickstart and python local demo docs to pass stream_response=True
• show streamed output by iterating over response.output as AgentStreamResponse chunks

Why this is a local SDK/docs issue

The current Python examples show streaming usage that does not match the local AgentSquad.route_request() implementation in python/src/agent_squad/orchestrator.py. In the Python SDK, streamed chunk iteration happens when stream_response=True is passed and response.output is consumed as an async stream.

Validation

• verified the route_request(..., stream_response=False) signature and streaming branch in python/src/agent_squad/orchestrator.py
• verified the updated examples now match that behavior

Fixes #220

[cornelcroi]

Hey @sztoplover-bit, both fixes are correct — the nested would silently exhaust the iterator and produce no output, and the missing meant callers would never get streaming. The import fix is also right. Just needs CI to go green before merging.