auto-triage: allow Empty media (zero compounds) without ValueError

[jplfaria]

Summary

• Fix _apply_media in src/modelseed_api/jobs/tasks.py to distinguish Empty media (zero mediacompounds) from the case where compounds are present but none match model exchange reactions. Empty media now closes all exchanges (cobra_model.medium = {}); the no-match case remains a warning-only path.
• Add regression tests in tests/unit/test_load_media_and_apply_media.py covering both _load_media (empty compounds no longer raises) and _apply_media (empty media closes all exchanges, no-match is a warning, non-empty media opens the right exchanges).

Fixes ModelSEED/modelseed-api-ops#34

Root cause

The Empty workspace object at /chenry/public/modelsupport/media/Empty intentionally has zero mediacompounds, meaning all exchanges closed. The _apply_media function was treating empty media identically to the no-match case, leaving default exchange bounds instead of closing all exchanges.

Test plan

• Run pytest tests/unit/test_load_media_and_apply_media.py -v -- all 6 tests pass
• Confirm FBA jobs with Empty media complete without error and return zero growth
• Confirm FBA jobs with non-empty media still work correctly

Generated with Claude Code

[jplfaria]

Superseded by a9b7a72, which fixes Empty-media handling in both Celery and subprocess FBA paths, preserves malformed-payload errors, and includes regression coverage. That commit is deployed and production biological acceptance passed: https://github.com/ModelSEED/modelseed-api/actions/runs/36621735683