cleanup: remove redundant TODO comment in Vector3.js

[MOHITKOURAV01]

Related issue: #32362

Description

This PR removes a redundant TODO comment in src/math/Vector3.js that was causing confusion. The comment // TODO lengthSquared? appeared above the lengthSq() method, suggesting the method might need to be renamed or implemented differently.

However, the lengthSq() method is already correctly implemented and follows the project's established naming convention of using the Sq suffix for methods that return squared values (similar to distanceToSquared(), manhattanDistanceTo(), etc.). The TODO comment was outdated and misleading, so it has been removed to improve code clarity.

Changes:

• Removed the // TODO lengthSquared? comment from line 747 in src/math/Vector3.js

Testing:

• All unit tests pass (npm run test-unit)
• Linting passes (npm run lint)
• No functional changes to the codebase

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	350.29 83.05	350.29 83.05	+0 B +0 B
WebGPU	612.89 170.29	612.89 170.29	+0 B +0 B
WebGPU Nodes	611.49 170.01	611.49 170.01	+0 B +0 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	482.23 117.82	482.23 117.82	+0 B +0 B
WebGPU	683.78 186	683.78 186	+0 B +0 B
WebGPU Nodes	633.61 173.18	633.61 173.18	+0 B +0 B

[mrdoob]

This PR removes a redundant TODO comment in src/math/Vector3.js that was causing confusion

Sorry for confusing you! Hope you can move on with your day 🤞