build_instrument drew a circle for every type, so `computer` shipped as
circle + hexagon and `plc` as circle + square + diamond (10 of the 20 bubble
blocks wrong, and the circle poked 0.67 mm outside the hexagon's flat top).
Spec 4.4: discrete = circle; dcs = circle inside a square; computer =
hexagon; plc = diamond inside a square. The outline is now chosen per type.
Location lines were always drawn from -r to +r, overshooting the hexagon's
slanted sides by 0.46 mm at y=+/-0.8 and the circle's chord by 0.06 mm.
They now end on the outline (`_bubble_half_width`): chord for the circle,
full width for the square, `r - |y| / tan 60` for the hexagon.
Tests now assert the exact primitive list per type and that every location
line stays on/inside its outline (both fail against the previous code).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
