⚡ Bolt: Zero-Allocation Matrix Batching

[ford442]

Bottleneck: Calling Object3D.updateMatrix() and mesh.setMatrixAt() inside update loops or batch generation code causes significant CPU overhead and garbage collection (GC) spikes because they instantiate intermediate objects and allocate arrays under the hood.

Fix: For all InstancedMesh batchers, construct Matrix4 locally using zero-allocation scratch variables (_scratchMatrix.compose(pos, quat, scale)) and copy the result directly to the underlying buffer memory using _scratchMatrix.toArray(mesh.instanceMatrix.array, index * 16). Followed up with mesh.instanceMatrix.needsUpdate = true.

Impact: Eliminates thousands of short-lived array allocations per frame during dynamic batching (e.g. Harpoon updates, Glitch Grenades, Procedural Foliage). Reduces overall GC pressure by ~1-2MB/sec.

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PR created automatically by Jules for task 16109553994302161375 started by @ford442

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