- Play a soft thunder SFX (sfx_thunder_01..04 at volume 0.35) on the
strobe's 0→>0 edge, once per strike; mid-strobe frames stay silent.
- Move `wasOn` latch after the thunder check so it reflects the previous
frame's state (fixes arm-frame and edge detection).
- Add `thunder: false` config to silence the voice while keeping the bolt.
- Cover with tests: arm frame silent, one clap per strike, mute path.
- New NebulaLightning visual: jagged edge-to-edge bolt with branches,
strobed in the gas base/accent colors, plus a soft distant thunder clap
- Pure seeded math (boltStrobe, strikeCycle, boltShape) in SystemEffectsMath,
Node-tested for determinism and shape correctness
- Wired into GameScene create/update/destroy lifecycle
- Config block in data/systems.json types.nebula.effect.lightning; docs
updated with tuning notes and smoke-game probe (?lightning=1&forceStrike=1)
Brian Fertig