chore(examples): share one operation-status reader across the demos

[jfrench9]

Summary

Six demos polled async operations through the same twelve-line dance, branching on the response body's shape to extract status and result:

status_data = status_resp.parsed
if isinstance(status_data, dict):
    status = status_data.get("status")
elif hasattr(status_data, "additional_properties"):
    props = status_data.additional_properties
    status = props.get("status")
else:
    status = getattr(status_data, "status", None)   # could never fire

The operations endpoints are declared as free-form objects, so the generated model carries only additional_properties and attribute access on it raises — that middle branch is the workaround, and the getattr fallback beneath it was unreachable. This is the consumer-side echo of the client defect fixed in RoboFinSystems/robosystems-python-client#202: everyone hit the wall and hand-rolled the same escape.

Changes

• examples/_common/sdk.py — operation_status(client, operation_id) reads the body through to_dict() and returns a plain dict, or {} when the response carried no body.
• Six polling loops — _scenario/runner.py, custom_graph_demo/create_graph.py, roboinvestor_demo/main.py, roboledger_demo/main.py, seattle_method_demo/main.py, seattle_method_world_online/main.py — each drops the dance for the helper and swaps the generated import for it. Net −99/+61 across seven files.

Behaviour is unchanged at every site. {} is falsy, so the existing continue still fires on an empty body; an error response or a body without a status key yields status is None, so the loop keeps polling rather than mistaking it for a terminal state — same as before.

Not touched

Three other additional_properties reads under examples/ — custom_graph_demo/memory_subgraph.py, custom_graph_demo/upload_documents.py, roboledger_demo/validate.py — read different response models (period-close overflow, an investor payload). The operations accessor does not apply, so they stay as they are.

This does not bump the client pin. The helper only needs to_dict(), which has always been generated, so it works against the currently-locked 1.13.1. Moving to 1.13.2 (for the query/operator/operations retry parity in #202) is worth doing on its own merits and belongs in its own change.

Testing

• just test-code — ruff, format and basedpyright clean. Note examples is in ruff's exclude list in pyproject.toml, so the tree is deliberately unlinted; these edits match the surrounding style by hand rather than by running a formatter over an excluded path.
• All seven touched modules import clean.
• operation_status exercised against a live stub for four cases: a completed operation (result.graph_id read back), a failed one, a 500 error body, and a 200 whose body omits status — the last two yielding status is None so a poll continues.
• The demos themselves need a live stack; not run end-to-end here.