- Grip points in paper space now use the 2-D linear to_px transform
(tx/ty/ortho_size) instead of the 3-D view_proj matrix, matching the
coordinate system used by PaperCanvas
- world_offset is no longer subtracted from paper-space entity grip
positions — paper-space coordinates are already unoffset (same rule
as wire tessellation in wires_for_block)
- MTEXT v_offset corrected for all attachment points: CXF glyphs sit
on the baseline and extend upward, so Top attachment needs v_offset=-h,
Bottom needs (n_lines-1)*line_h, Middle is the midpoint of the two
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>