Point clouds: attach dialog, crop toolbar, stylize, palette rows

POINTCLOUDATTACH opens the Attach Point Cloud dialog after the file is
chosen; its Attach button lives in the Attach Underlay list instead of a
separate Insert panel. A selected cloud brings the crop tools to the
right-edge toolbar. POINTCLOUDSTYLIZE sets the stylization with the
reference's prompts, the External References palette lists point clouds
(unload, reload, detach, path), and definitions keep the header extents.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/entities/extended.rs

@@ -1273,20 +1273,7 @@ fn apply_point_cloud_ex_prop(data: &mut PointCloudExData, field: &str, value: &s
                 .iter()
                 .find(|(name, _)| value == t!(*name).as_ref() || value.eq_ignore_ascii_case(name))
             {
-                data.stylization_type = *stylization;
-                // Intensity and elevation start from their default schemes,
-                // Spectrum and Earth.
-                let default = match stylization {
-                    5 => Some(POINT_CLOUD_RAMPS[6].1),
-                    4 => Some(POINT_CLOUD_RAMPS[1].1),
-                    _ => None,
-                };
-                if let Some(default) = default {
-                    let slot = point_cloud_scheme_slot(data);
-                    if slot.is_empty() {
-                        *slot = default.to_string();
-                    }
-                }
+                set_point_cloud_stylization(data, *stylization);
             }
         }
         "ext_pcx_color_scheme" => {
@@ -1326,6 +1313,23 @@ fn apply_point_cloud_ex_prop(data: &mut PointCloudExData, field: &str, value: &s
     }
 }
 
+/// Sets a cloud's stylization (its stored value); intensity and elevation
+/// start from their default schemes, Spectrum and Earth.
+pub(crate) fn set_point_cloud_stylization(data: &mut PointCloudExData, stylization: i16) {
+    data.stylization_type = stylization;
+    let default = match stylization {
+        5 => Some(POINT_CLOUD_RAMPS[6].1),
+        4 => Some(POINT_CLOUD_RAMPS[1].1),
+        _ => None,
+    };
+    if let Some(default) = default {
+        let slot = point_cloud_scheme_slot(data);
+        if slot.is_empty() {
+            *slot = default.to_string();
+        }
+    }
+}
+
 /// Rejects what the reference rejects before a point cloud row is written.
 pub(crate) fn validate_point_cloud_property(field: &str, value: &str) -> Result<(), &'static str> {
     if field == "ext_pcx_scale" && !parse_f64(value).is_some_and(|scale| scale > 0.0) {