WebGPURenderer: Fix texture view caching and dispose event stacking

[RenaudRohlinger]

Related issue: #30560

Description

In the WebGPU backend before r172, there was a bug where renderTarget.activeMipmapLevel was incorrectly used instead of renderContext.activeMipmapLevel. This was partially fixed in PR #30155:
https://github.com/mrdoob/three.js/pull/30155/files#diff-dab3c57cef925d356099192da6cb6710336ac50052d2f6774897e1864d8c46a9L305-R331

However, my commit missed updating the cache invalidation condition:

• Current: renderTargetData.activeMipmapLevel !== renderTarget.activeMipmapLevel
• Should be: renderTargetData.activeMipmapLevel !== renderContext.activeMipmapLevel

This oversight exposed two critical memory leaks:

1. The dispose event listener was being added repeatedly without proper cleanup, as cache invalidation was triggered incorrectly.

2. The caching strategy for texture views in _getRenderPassDescriptor was inefficient. It should separate the caching into two steps:

   • Cache expensive texture views based on target dimensions and mipmap/face properties
   • Apply dynamic properties (loadOp, storeOp, clearValue) on demand without recreating views

Additionally, texture views in the clear() method were never cached at all, resulting in new views being created for every clear operation, accumulating indefinitely.

I investigated this issue following memory leaks on a Windows project that ultimately crashed the GPU after running for a few hours. This suggests different platforms may handle GPU resource accumulation and cleanup differently, with Windows potentially being less forgiving.

Before this PR: Texture views infinitely accumulating, consuming GPU memory that may not be promptly released even after JavaScript references are no longer used.

(But you can test any WebGPU example and will see the texture views accumulating and onDispose event stacking.)

After (Texture Views reduced and cached to 79):

This contribution is funded by Utsubo

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.02 78.26	336.02 78.26	+0 B +0 B
WebGPU	523.26 145.3	523.81 145.44	+551 B +135 B
WebGPU Nodes	522.73 145.2	523.28 145.33	+551 B +135 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.06 112.14	465.06 112.14	+0 B +0 B
WebGPU	593.67 160.91	594.22 161.04	+551 B +130 B
WebGPU Nodes	548.79 150.34	549.34 150.47	+551 B +130 B