Plan §5055: Attack event arrows from killers to victim position.
Added 3 tests to verify:
1. Arrows are drawn from each killer to victim in combat_death events
2. Multiple arrows are drawn for multiple killers (2v1 situations)
3. Arrow colors are set based on attacker player color
The tests mock the canvas context and verify that the appropriate
drawing methods (moveTo, lineTo, stroke, fill) are called when
rendering turns with combat_death events.
Closes: bf-4o9fp
