fix: prevent overlapping pin labels in custom symbols

[techmannih]

Summary

Fixes overlapping pin labels in compact custom schematic symbols such as C113367.

Changes

• Preserves original EasyEDA polarity labels for schematic display:
  • IN- instead of IN_NEG
  • VO+ instead of VO_POS
• Retains normalized aliases such as IN_NEG and VO_POS for connectivity and selectors.
• Adds extra spacing for compact custom symbols with normalized polarity labels.
• Keeps active-low and regular pin-label behavior unchanged.
• Updates C113367 inline and schematic snapshots.
• Adds parser and symbol-generation regression coverage.
• Includes schematic and PCB snapshot coverage.

Validation

• 34 parser and custom-symbol regression tests pass.
• Full C113367 conversion tests pass.
• Production build passes.
• Updated schematic was visually verified to contain no overlapping pin labels.

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