Covers the three bugs fixed in the previous commit:
- TestAddComponentNoTrailingUnderscore (integration): verifies clone() + no extra append()
- TestPinLocatorYAxisNegation (unit): rotation=0 and 90° cases with y-negation
- TestPinLocatorReferenceRstrip (unit): lookup tolerates 'R1_' artifact from kicad-skip
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>