- Split the shared `fire` event into `cannon_fire`, `cannon_hit`, and `fire` so each weapon gets its own distinct voice
- Add three new sound assets (combat-mass-cannon, combat-mass-cannon-hit, combat-laser) to data/sfx.json and load them in GameScene
- Remove the 0.45 volume multiplier on enemy fire; the laser now plays at full volume since it has its own voice
- Update CombatSfx event map, both combat contexts (CombatScene, CombatSystem), dev tests, and README to reflect the ten-event SFX set