changelog.md for @fin.cx/calculation

[1.0.0] - 2025-07-29

Added

• Initial release of @fin.cx/calculation
• Calculator class with high-precision decimal arithmetic
• Financial class with time value of money calculations (PV, FV, NPV, IRR, XIRR)
• Interest class with simple, compound, and continuous interest calculations
• Amortization class with loan schedules and payment analysis
• Currency class with conversion, formatting, and monetary operations
• Comprehensive test suite
• Full TypeScript support
• CI/CD workflows for automated testing and publishing