Guide sketch patterns with live previews and editable offsets (#966)

Sketch Mirror, rectangular and circular Pattern, and Offset now show a green live preview that follows the selection and settings; OK commits, Cancel leaves the sketch unchanged. The shared dialogs show the current selection step and source counts, sources can be toggled with Ctrl/Cmd-click, cleared and reselected.

Offsets keep editable driving distance dimensions (One Side, Two Sides, Symmetric) that update the derived curves without moving the source, with undo/redo and save/reopen. Format 19: older files keep their fixed offsets.

New dialog labels in en, zh, ja, de and ko.

Fixes #696. Fixes #517.

crates/ui-egui/src/selection.rs

@@ -36,6 +36,8 @@ pub const CURVES: Accept = 256;
 pub const POINTS: Accept = 512;
 /// Timeline features (pattern objects), picked in the timeline.
 pub const FEATURES: Accept = 1024;
+/// Points of the sketch being modified; unlike POINTS these never enable cross-sketch picking.
+pub const SKETCH_POINTS: Accept = 2048;
 
 /// One selection input of a command dialog ("Profiles", "Edges", "Plane", ...).
 #[derive(Clone, Debug, PartialEq)]
@@ -66,6 +68,7 @@ impl SelInput {
             Hit::Axis { name } if a & AXES != 0 => Some(Sel::Axis { name: name.clone() }),
             Hit::SketchCurve { id, straight: true, .. } if a & AXES != 0 => Some(Sel::SketchCurve { id: id.clone() }),
             Hit::SketchCurve { id, .. } if a & CURVES != 0 => Some(Sel::SketchCurve { id: id.clone() }),
+            Hit::SketchPoint { id, .. } if a & SKETCH_POINTS != 0 => Some(Sel::SketchPoint { id: id.clone() }),
             Hit::SketchPoint { sketch, id, .. } if a & POINTS != 0 => Some(Sel::SketchPoint { id: format!("{sketch}:{id}") }),
             Hit::Vertex { body, point } if a & VERTICES != 0 => Some(Sel::Vertex { body: body.clone(), point: *point }),
             _ => None,