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/sketch/src/lib.rs

@@ -45,7 +45,9 @@ pub use dims::{DimFrame, DimLayout, chain_centres, default_text, dim_frame, dim_
 pub use fonts::{DEFAULT_FONT_FAMILY, FontData, families_in, find_style_in, font_data, font_data_styled, font_file_path, installed_families};
 pub use freeform_offset::{FreeformOffset, OFFSET_TOLERANCE};
 pub use link::{Link, LinkGeom, LinkKind, LinkSource, MAX_LINK_ENTITIES, SKETCH_AXIS_HALF, sketch_axis_geom};
-pub use model::{Constraint, ConstraintKind, Curve, CurveKind, MAX_CONSTRAINTS, MAX_CURVES, MAX_POINTS, SPoint, Sketch, SketchError, SketchView};
+pub use model::{
+    Constraint, ConstraintKind, Curve, CurveKind, MAX_CONSTRAINTS, MAX_COORD, MAX_CURVES, MAX_POINTS, SPoint, Sketch, SketchError, SketchView,
+};
 pub use offset::OffsetChain;
 pub use offset_topology::{OffsetCreated, OffsetRole, OffsetRoleFlags, OffsetRoleKind, OffsetTopology};
 pub use periodic::periodic_beziers;