MSAA and depth textures are now sized to the shader widget's clip
bounds instead of the full surface. The resolve writes to a matching
clip-sized intermediate texture; a blit pass (blit.wgsl, viewport
trick) then copies the result to the exact clip region of the surface
target, leaving all other widgets untouched.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>