feat: Implement supplier export functionality with workbook generation

- Add `writeSupplierWorkbook` function to create Excel workbooks for supplier analysis results.
- Introduce `SupplierExportSummary` type for summarizing export data.
- Create tests for `writeSupplierWorkbook` to ensure correct sheet creation and data population.
- Implement supplier scoring logic in `supplier-scoring.ts` to evaluate product profitability and demand.
- Add tests for supplier scoring to validate scoring logic and verdict determination.
- Enhance UPC file analysis to integrate supplier scoring and export results to Excel.
- Update database writing logic to accommodate new supplier analysis results.
- Refactor types to include supplier-specific data structures and scoring metrics.
- Ensure proper cleanup of temporary files after tests.

.gitignore

@@ -6,6 +6,11 @@ out
 dist
 *.tgz
 
+# local data directories
+input/*
+output/*
+db/*
+
 # code coverage
 coverage
 *.lcov
@@ -32,18 +37,6 @@ report.[0-9]_.[0-9]_.[0-9]_.[0-9]_.json
 
 # Finder (MacOS) folder config
 .DS_Store
-*.xlsx
-
-results.db
-
-results.db-shm
-
-results.db-wal
-
-output/
-
 temp_output/
 
 dist-server/
-
-*.xls