Add unit tests for pack system
Add comprehensive test coverage for CardPack, PackSlot, DefaultPackSlots,
and PackParser classes. Tests verify TypeID generation, slot weight
configurations, file parsing with various formats, and default pack creation.
Test coverage:
- CardPack: GenerateTypeID consistency and uniqueness
- PackSlot: Default values, rarity/card weight population
- DefaultPackSlots: Slot weight distributions, GetDefaultSlots
- PackParser: File parsing, multiple packs/slots, card-specific weights
Total: 60 tests (29 existing + 31 new)
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Co-Authored-By: Claude <noreply@anthropic.com>
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