Point clouds: POINTCLOUDCOLORMAP dialog, out-of-range colouring

POINTCLOUDCOLORMAP asks for a cloud (or None for the drawing's default
schemes) and opens the Point Cloud Color Map dialog: intensity and
elevation tabs with the scheme list, New / Delete / Rename, number of
colours (2-25, resampled along the scheme), blend between the ends,
reverse, gradient or bands, the colorized range, the out-of-range
choice and, for elevation, the cloud's extents or a fixed range with its
band height. OK / Apply write the drawing's colour map (created under
ACAD_POINTCLOUD_COLORMAP_DICT when missing) and the cloud's colouring in
one undo step; Make stylization current sets the tab's stylization.
Values outside a scheme's range take the end colours, the scan colours
or are hidden. Automation action pc_colormap edits the dialog.

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

src/entities/extended.rs

@@ -1130,6 +1130,11 @@ pub(crate) const POINT_CLOUD_RAMPS: [(&str, &str); 7] = [
     ("Spectrum", "C0A3838B-81E3-4506-B908-13ECF523DB68"),
 ];
 
+/// A built-in scheme's identifier by name (Blues when unknown).
+pub(crate) fn point_cloud_ramp_id(name: &str) -> &'static str {
+    POINT_CLOUD_RAMPS.iter().find(|(n, _)| *n == name).unwrap_or(&POINT_CLOUD_RAMPS[0]).1
+}
+
 /// Stylization choices in the order the reference lists them, with the
 /// stored values: scan colours 1, object colour 2, normals 3, intensity 5,
 /// elevation 4.