Defer quickstart Data/Query creation to runtime

[anthonydellapia1117]

Why

Importing scripts/quickstart.py caused pytest and other tooling to exit at import time when Yahoo API credentials were not present. This created an unexpected side effect: test collection and imports failed unless environment variables or credentials were set.

What changed

• Move creation of Data and YahooFantasySportsQuery into a create_query() helper.
• Instantiate Data and the query only when running the script directly (under if name == "main").

This prevents import-time OAuth work and avoids exiting during module import, allowing test discovery and other tooling to import quickstart.py safely.

Notes and testing

• Unit test collection now succeeds without Yahoo credentials (integration tests still require credentials or Docker). 44 tests were deselected during a unit-only run.
• No behavior changes when running the script directly; quickstart still constructs its Data/query and runs as before when executed.

If reviewers prefer a different helper name or placement, happy to adjust.