Per-frame CreateRaytracingAccelerationStructure calls during F3 animation
caused VRAM explosion (especially toping BLAS at ~23M vertices). Now all
3 BLASes use capacity-based allocation with 25% headroom — only recreated
when vertex count exceeds capacity, otherwise just BuildRaytracingAS with
updated desc.vertex_count. TLAS only recreated when instance count changes.
Also adds deferred toping BLAS position upload via UpdateBuffer in Render()
(topingBLASDirty_ flag), enabling toping shadows to update during animation.
Split CLAUDE.md into CLAUDE.md + TROUBLESHOOTING.md for maintainability.
