PCEXTRACTSECTION: Extract Section Lines dialog

Picking the cloud opens the Extract Section Lines from Point Cloud
dialog with the reference's settings and defaults: entire cross section
or perimeter only, maximum points to process (slider and field, with
the estimated time), output layer (Use Current or a layer), colour,
lines or 2D polylines with their width, minimum line length and connect
lines tolerance (each measurable by two points on screen), collinear
angle tolerance (0-10) and Preview result. Create extracts; with the
preview it asks [Accept/Settings/Undo] and Settings reopens the dialog.
The settings are kept for the session. Automation action pc_section.

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

src/app/mod.rs

@@ -499,6 +499,7 @@ pub(super) struct OpenCADStudio {
     pdf_attach: Option<crate::ui::window::pdf_dialogs::PdfAttachState>,
     point_cloud_attach: Option<crate::ui::window::pdf_dialogs::PointCloudAttachState>,
     point_cloud_color_map: Option<crate::ui::window::pdf_dialogs::PointCloudColorMapState>,
+    pc_section: Option<crate::ui::window::pdf_dialogs::PcSectionState>,
     underlay_layers: Option<crate::ui::window::pdf_dialogs::UnderlayLayersState>,
     pdf_import_settings: Option<crate::modules::insert::pdf_import::PdfImportSettings>,
     pdf_import_file: Option<crate::ui::window::pdf_dialogs::PdfImportFileState>,
@@ -1907,6 +1908,7 @@ pub enum ModalKind {
     PdfAttach,
     PointCloudAttach,
     PointCloudColorMap,
+    PcSection,
     UnderlayLayers,
     PdfImportSettings,
     PdfImportFile,
@@ -4041,6 +4043,7 @@ impl OpenCADStudio {
             pdf_attach: None,
             point_cloud_attach: None,
             point_cloud_color_map: None,
+            pc_section: None,
             underlay_layers: None,
             pdf_import_settings: None,
             pdf_import_file: None,