feat(core): initial release of financial calculation package with decimal precision

readme.hints.md

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+# Project Hints
+
+## Architecture
+
+This project follows the @push.rocks/smartstate pattern with the following structure:
+- TypeScript source files in `ts/` directory
+- Test files in `test/` directory
+- Built files output to `dist_ts/` directory
+- ES modules configuration (`"type": "module"`)
+
+## Key Design Decisions
+
+1. **Decimal Precision**: Uses decimal.js library to avoid JavaScript floating-point errors
+2. **Class Hierarchy**: Calculator is the base class, other classes extend it for specific domains
+3. **Naming Convention**: Files follow pattern `calculation.classes.*.ts`
+4. **Plugin Pattern**: Dependencies are imported through `calculation.plugins.ts`
+
+## Development Workflow
+
+1. Run tests: `pnpm test`
+2. Build project: `pnpm build`
+3. Type checking: `tsbuild check test/**/* --skiplibcheck`
+4. Testing uses @git.zone/tstest with expect from @push.rocks/tapbundle
+
+## Financial Calculations
+
+- All monetary calculations use decimal arithmetic for accuracy
+- Interest calculations support multiple compounding frequencies
+- Financial functions follow standard financial formulas
+- Currency class handles formatting based on locale conventions
+
+## Testing Strategy
+
+- Cross-platform tests in `test.both.ts`
+- Tests cover accuracy, edge cases, and error handling
+- Precision tests ensure decimal accuracy is maintained