- Add lightningArcMeta array to track per-arc active state and base opacity
- Per-frame opacity flicker (55–100% of base) applied each animation frame for
realistic lightning appearance between geometry refreshes (130ms interval)
- Arc color now blends between source and destination crystal colors via lerpColor()
instead of a random crystal color, giving each arc visual context
- Crystal emissive flash: struck crystals boost emissiveIntensity and point light
intensity for 250ms when an arc connects, giving visible impact feedback
- Pass elapsed time into updateLightningArcs() for flash timing
Fixes#243
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>