feat: add supplier scoring and UPC file analysis functionality

- Implemented supplier scoring logic in `supplier-scoring.ts` with functions to compute demand score, competition penalty, and overall supplier product score.
- Created unit tests for supplier scoring in `supplier-scoring.test.ts` to validate scoring logic against various scenarios.
- Developed UPC file analysis tool in `upc-file-analysis.ts` to process UPCs in batches, fetch product data from Keepa and SP-API, and generate supplier results.
- Added UPC input reading functionality in `upc-file-reader.ts` to handle XLSX and XLS files, including validation for UPC formats.
- Introduced a command-line tool in `upc-lookup.ts` for looking up UPCs and displaying detailed results or mappings to ASINs.
- Enhanced error handling and logging throughout the new modules for better traceability and user feedback.

package.json

@@ -4,13 +4,13 @@
   "type": "module",
   "private": true,
   "scripts": {
-    "bestsellers": "bun run src/bestsellers-by-category.ts",
-    "monthly-sold": "bun run src/top-monthly-sold-by-category.ts",
-    "mid-range": "bun run src/mid-range-sellers-by-category.ts",
-    "stalker": "bun run src/stalker.ts",
+    "bestsellers": "bun run src/categories/bestsellers-by-category.ts",
+    "monthly-sold": "bun run src/categories/top-monthly-sold-by-category.ts",
+    "mid-range": "bun run src/categories/mid-range-sellers-by-category.ts",
+    "stalker": "bun run src/stalker/stalker.ts",
     "search-offers": "bun run src/asin-offer-search.ts",
-    "upc": "bun run src/upc-lookup.ts",
-    "upc-file": "bun run src/upc-file-analysis.ts",
+    "upc": "bun run src/supplier/upc-lookup.ts",
+    "upc-file": "bun run src/supplier/upc-file-analysis.ts",
     "start": "bun run src/index.ts",
     "start:web": "bun --hot src/server.ts",
     "build:web": "bun build src/web/index.html --outdir dist",