feat: add UPC to ASIN mapping and large file UPC analysis

Introduces the capability to resolve UPCs to ASINs using the Keepa API. This includes a new `upc-file` command for processing large Excel files of UPCs, a `upc` CLI tool for quick lookups, and API endpoints for web-based integration. The analysis pipeline was refactored into a reusable module to support both standard ASIN leads and new UPC-driven workflows.

package.json

@@ -6,6 +6,8 @@
   "scripts": {
     "bestsellers": "bun run src/bestsellers-by-category.ts",
     "monthly-sold": "bun run src/top-monthly-sold-by-category.ts",
+    "upc": "bun run src/upc-lookup.ts",
+    "upc-file": "bun run src/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",
@@ -21,6 +23,7 @@
   },
   "dependencies": {
     "amazon-sp-api": "^1.2.1",
+    "exceljs": "^4.4.0",
     "ioredis": "^5.10.1",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",