- Updated shader grid rendering to intersect the grid plane in view space and draw it with a single full-screen triangle.
- Added shader grid bounds to camera Z-fit, so the grid is visible in empty views and after object display without an extra vfit.
- Fixed shader grid echo to use the active shader grid plane, effective scale, bounds and clip-safe display point.
- Kept the viewer-managed CPU grid path separate from the per-view shader grid path and preserved CPU grid type/mode handling in vgrid.
- Added grid tests for empty/no-vfit visibility and perspective rendering without mirrored fragments.