Replace the single stacked config pane with a top tab strip (Pack, Cells, BMS,
Busbars) so only one group is visible at a time. Pack sizing defaults to
Series × Parallel with a summary chip that shows count and footprint, with a
mm-size mode for users who prefer direct dimensions. Cells and Housing are
merged under one tab separated by a divider.
Exports are now per component: the cellholder is a STEP solid, and each busbar
downloads as either STEP (3D stencil) or DXF (flat laser cut pattern) chosen by
a dropdown. Mirrored and rotated duplicates are deduplicated by a
pairwise-distance signature so only one copy per shape class is emitted.
The DXF writer produces just the union outline: pads as CIRCLE or ARC entities
restricted to uncovered angular ranges, capsule sides as LINE entities clipped
(Liang-Barsky + disc intersection) against every other primitive so no lines
remain inside the busbar body.
README documents setup, features, and project layout.
Pan/zoom handlers redraw the cell holder canvas but skipped the busbar overlay, which was only drawn from updatePreview(). Cache the last draw args and expose redrawBusbarOverlay() so the overlay stays visible during wheel, drag, and touch interactions.
