Align Python SDK contracts with retrieval and job APIs

[suguanYang]

Summary

• expand retrieval.query(...) to accept the current API request schema and expose router_used on responses
• stop exposing document_id on Job create responses while preserving published document scope on JobResult and loaded ParseResult
• update README examples and tests to use job_result.document_id instead of job.document_id

Validation

• uv run pytest tests/test_jobs.py tests/test_retrieval.py tests/test_parse.py tests/test_models.py -q
• uv run pytest -q
• uv run ruff check .
• uv run mypy src