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.

src/integrations/sp-api.test.ts

@@ -0,0 +1,46 @@
+import { expect, test } from "bun:test";
+import { parseCatalogUpcLookupResponse } from "./sp-api.ts";
+
+test("parseCatalogUpcLookupResponse resolves one ASIN", () => {
+  const detail = parseCatalogUpcLookupResponse("012345678901", {
+    items: [{ asin: "b000found1" }],
+  });
+
+  expect(detail.status).toBe("found");
+  expect(detail.asin).toBe("B000FOUND1");
+  expect(detail.candidateAsins).toEqual(["B000FOUND1"]);
+});
+
+test("parseCatalogUpcLookupResponse marks no match", () => {
+  const detail = parseCatalogUpcLookupResponse("012345678901", {
+    payload: { items: [] },
+  });
+
+  expect(detail.status).toBe("not_found");
+  expect(detail.asin).toBeNull();
+});
+
+test("parseCatalogUpcLookupResponse marks multiple ASINs", () => {
+  const detail = parseCatalogUpcLookupResponse("012345678901", {
+    payload: {
+      items: [{ asin: "B000000001" }, { asin: "B000000002" }],
+    },
+  });
+
+  expect(detail.status).toBe("multiple_asins");
+  expect(detail.candidateAsins).toEqual(["B000000001", "B000000002"]);
+});
+
+test("parseCatalogUpcLookupResponse marks invalid UPCs", () => {
+  const detail = parseCatalogUpcLookupResponse("123", { items: [] });
+
+  expect(detail.status).toBe("invalid_upc");
+});
+
+test("parseCatalogUpcLookupResponse marks malformed response as failed", () => {
+  const detail = parseCatalogUpcLookupResponse("012345678901", {
+    unexpected: true,
+  });
+
+  expect(detail.status).toBe("request_failed");
+});