Point clouds: drawn from their scans, placed, cropped and attached as the reference does

Scans (.rcs) and projects (.rcp) are read and their points drawn as
screen-sized dots, coloured by the cloud's stylization. The cloud's
placement carries its scale and rotation; its extents and crops stay in
the scan's coordinates. A missing scan shows the extents with the saved
path. -POINTCLOUDATTACH / POINTCLOUDATTACH, POINTCLOUDCROP and the
POINTCLOUD* settings follow the reference's prompts and messages, the
Properties list is the reference's, and a locked cloud is left alone by
edits.

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

src/modules/draw/select.rs

@@ -196,6 +196,13 @@ impl CadCommand for SelectObjectsCommand {
         self.associative_dimensions_only
     }
 
+    fn selection_drops_locked_point_clouds(&self) -> bool {
+        matches!(
+            self.pending_cmd.as_str(),
+            "MOVE" | "3DMOVE" | "ROTATE" | "3DROTATE" | "SCALE" | "MIRROR" | "MIRROR3D" | "STRETCH"
+        )
+    }
+
     // Clickable selection keywords (#426, #596). Window and Crossing fix the
     // sense of the next box, which dragging would otherwise take from the
     // direction the corner travels; All takes the whole space; Add and Remove