Fix significant FPS drop with mask usage.

[notKitory]

Summary
Orphan dynamic WebGL buffer storage before uploading new batch data.
Prevent progressive GPU synchronization stalls during repeated dynamic buffer updates.
Keep STATIC_DRAW buffer behavior unchanged.

Description
WebGLBufferWrapper.update() reused the same GPU storage for every bufferSubData() call. When dynamic geometry was rendered repeatedly—especially across offscreen and onscreen passes—the browser could wait for queued GPU work that was still using that storage. This caused frame time to increase progressively, even though JavaScript memory and renderer pools remained stable.

Before uploading data for non-static buffers, this change calls bufferData() with the existing buffer size and usage. This orphans the previous storage, allowing queued GPU commands to finish using it while the next batch is uploaded into fresh storage.

The following bufferSubData() behavior remains unchanged, and STATIC_DRAW buffers are not affected.

Fixes #7306

Testing
Manually tested with a stress scene that updates Shape geometry inside a DynamicTexture every frame and uses it as a mask. Tested on MacBook Air M4 and Redmi Note 14.

Verified that:

• Dynamic mask rendering remains stable over time.
• Detached DynamicTexture rendering remains stable.
• Framebuffer-only and static-mask control modes remain stable.
• RexUI Scrollable objects no longer exhibit progressive FPS degradation.
• JavaScript heap usage and renderer pool sizes remain stable.

node --check src/renderer/webgl/wrappers/WebGLBufferWrapper.js