Add unit tests for catalyst.py

[DogInfantry]

Summary

catalyst.py currently has no test coverage. Add unit tests under tests/ to cover the catalyst calendar builder logic.

What to Test

• Calendar generation returns expected structure (list of dicts with date, ticker, event type)
• Edge cases: empty watchlist, future dates only, past dates only
• Output is sorted chronologically
• No live API calls in tests (use pytest-mock or responses to mock)

Files Involved

• trg_workbench/analytics/catalyst.py — source under test
• tests/test_catalyst.py — new file to create

Acceptance Criteria

• tests/test_catalyst.py created with at least 4 test cases
• All tests pass with pytest
• No live network calls in the test suite
• Follows existing test conventions in the tests/ folder

Notes

No deep financial knowledge required — focus on input/output correctness and edge case handling.