feat: API Server - Pipeline run search - Validate TimeRange bound ordering (#162)

[shuofengzhang]

What changed

• Added TimeRange model validation to reject ranges where start_time is later than end_time.
• Updated TimeRange docstring to document the bound-order requirement when both timestamps are provided.
• Added a regression test (test_time_range_rejects_start_after_end) in tests/test_filter_query_models.py.

Why

• A reversed time window is almost always a caller error.
• Rejecting invalid ranges early in request validation provides clearer feedback and avoids executing contradictory SQL predicates.

Testing

• ✅ .venv/bin/python -m pytest -q (298 passed)

[Ark-kun]

Thank you for your contribution.