SVGRenderer: Add near/far plane clipping support.

[mrdoob]

Related issue: #32111

Description

Implements proper near/far plane clipping for triangles in the SVGRenderer using the Sutherland-Hodgman clipping algorithm in homogeneous clip space.

Changes

• Projector.js: Added triangle clipping against near and far planes

  • Implements Sutherland-Hodgman algorithm in homogeneous clip space (before perspective divide)
  • Uses object pools to prevent garbage collection
  • Fast path for unclipped triangles (no clipping overhead when triangle is fully inside frustum)
  • Early rejection for completely clipped triangles

• SVGRenderer.js: Removed Z-coordinate checks for triangle vertices

  • Removed the three if ( _v1/v2/v3.positionScreen.z < -1 || > 1 ) checks
  • Clipping is now handled properly by the Projector before vertices reach the renderer