Rounded corners in gcode

[MarkJB]

This pull request adds a new "round sharp corners" feature to the G-code export workflow, allowing users to automatically smooth sharp polyline corners with arcs of configurable angle and radius. The implementation affects the user interface, data models, and the G-code generation logic. Additionally, it introduces infrastructure for re-clipping hatch lines against rounded boundaries and updates related types and state management.

New round-corner smoothing feature:

• Added new G-code export options for rounding sharp corners, including a checkbox to enable the feature and numeric fields for angle threshold and radius, with appropriate UI controls and validation in GcodeOptionsDialog.tsx. [1] [2] [3] [4]
• Updated the G-code options and preferences interfaces (GcodePrefs, GcodeOptions) and the toolbar to support the new round-corner parameters. [1] [2] [3]

G-code engine and SVG worker enhancements:

• Implemented robust algorithms in gcodeEngine.ts for rounding polyline corners (roundSubpathCorners) and for re-clipping hatch lines against rounded polygons (clipSegmentToPolygon).
• Integrated the new options and logic into the SVG worker, including passing round-corner parameters, updating G-code comments, and deferring hatch-line processing for accurate clipping. [1] [2] [3] [4]

Data model and state management updates:

• Extended the VectorObject type to include an optional hatchParentId property for hatch-fill lines, enabling correct association and re-clipping during G-code generation.
• Updated the canvasStore to set hatchParentId for generated hatch lines. [1] [2] [3]

[github-actions]

PR build artifacts are ready:

• Windows: pr-32-windows-24003115129
• macOS: not selected
• Linux: not selected

These artifacts are temporary and are deleted automatically when the PR is closed.