test: add repro for C2943786 asymmetric courtyard

[anil08607]

#505 (review)

Summary

Adds a focused regression test for the incorrectly generated C2943786 courtyard.

EasyEDA’s footprint BBox includes the offset pin-1 silkscreen marker, causing the fallback courtyard to expand toward the left and become asymmetric around the component body.

Reproduces

• Body center: 0 mm
• Courtyard center offset: -0.354 mm
• Left clearance: 0.958 mm
• Right clearance: 0.249 mm

Test coverage

• Adds an inline snapshot capturing the asymmetric courtyard measurements.
• Adds a PCB snapshot showing the oversized left-side courtyard.
• Uses test() following the repository test convention.