ASX: Fix factor_screen.py test fixtures (8 failed, 1 error)

Jun 25 test run showed 8 failures + 1 error in integration tests due to fixture mismatch in factor_screen.py. The signal_engine.py implements SMA crossover (Phase 1 design), NOT the dividend-factor-based V2 engine from the design doc. Need to fix test fixtures to match actual codebase state, and decide whether to rework signal_engine.py toward V2 spec or align tests to Phase 1 reality.

Note (2026-06-29T01:38:04Z)

Picked up by ralph at 2026-06-29T13:45+10. Reading factor_screen.py and its test file to understand the fixture mismatch.