MathUtils: Fix large isPowerOfTwo values

[lprnmns]

Problem

MathUtils.isPowerOfTwo() uses bitwise operators, which coerce numbers to 32 bits. Large non-powers such as 3 * 2 ** 32 therefore return true, despite the public API documenting a general number input.

Fix

Check for a positive integer and compare it exactly with the nearest numeric power of two. This avoids 32-bit truncation while keeping existing behavior.

Tests

• npm run test-unit - 1315 passed, 1 todo
• npm run test-unit-addons - 385 passed
• npm run lint-core - passed
• npm run build - passed
• git diff --check - passed

Compatibility

The signature is unchanged. Behavior changes only for values the previous 32-bit coercion classified incorrectly.

Related issue

Independently reproduced on current dev; no matching issue or pull request was found.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
Core	389.13 102.11	389.18 102.13	+43 B +20 B
WebGL	372.46 87.93	372.46 87.93	+0 B +0 B
WebGPU	709.03 195.26	709.03 195.26	+0 B +0 B
WebGPU Nodes	707.01 194.94	707.01 194.94	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	515.88 124.89	515.88 124.89	+0 B +0 B
WebGPU	762.69 204.82	762.73 204.84	+43 B +20 B
WebGPU Nodes	711.35 192.09	711.39 192.11	+43 B +21 B