Generate physically spaced plot fills

[jamiejk]

Parent

#1

What to build

Generate plotter-drawable interior fills with predictable physical spacing. Concentric fills use true constant-distance inward offsets and preserve region identity; parallel hatch remains an alternative. Neither fill style silently adds a boundary.

Acceptance criteria

• Concentric paths are true geometric inward offsets at constant physical spacing, not centroid-scaled copies.
• Regular and irregular convex regions maintain consistent edge-to-edge spacing within geometric tolerance.
• Concentric generation terminates cleanly when a region collapses or becomes too small.
• Paths belonging to one concentric region retain their shared region identity and outer-to-inner order.
• Parallel hatch paths are clipped to their region and the printable boundary.
• Both fill styles exclude the original region boundary unless Outline is also selected.
• Default spacing derives from the active pen profile's nib width, with a user-set physical override.
• Preparation tests cover regular, irregular, small, and paper-edge regions.

Blocked by

• Configure plot treatment by tile type #3
• Cover and clip the printable area at physical scale #5