CLIP on raster images and viewports, IMAGECLIP, VPCLIP, clip depth rules

- CLIP continues as IMAGECLIP on a raster image and as VPCLIP on a layout
  viewport, with the reference prompts and stored data.
- Image clip boundaries sit on pixel centres, OFF only clears the display
  flag, and an inverted boundary cuts the image.
- VPCLIP polygon (Arc/Length/Close/Undo), clipping object and Delete; the
  viewport shrinks to the boundary's exact extents, view kept.
- XCLIP Clipdepth: Remove clears only the plane asked, a front plane behind
  the back one is rejected with the reference message.
- Attached and imported images carry the reference display flags.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/modules/draw/draw/raster_image.rs

@@ -96,6 +96,7 @@ impl ImageCommand {
                     world_height,
                 );
                 img.flags = codec::entities::ImageDisplayFlags::SHOW_IMAGE
+                    | codec::entities::ImageDisplayFlags::SHOW_NOT_ALIGNED
                     | codec::entities::ImageDisplayFlags::USE_CLIPPING_BOUNDARY;
                 self.plane.place_entity(EntityType::RasterImage(img))
             }