feat: initialize asin-check project with Bun

- Add README.md with installation and usage instructions.
- Create bun.lock for dependency management.
- Add package.json to define project metadata and dependencies.
- Implement caching with Redis in cache.ts for ASIN data.
- Configure environment variables in config.ts for API keys and Redis URL.
- Develop main application logic in index.ts to read products, fetch data, and analyze results.
- Integrate Keepa API for product data retrieval in keepa.ts.
- Create LLM analysis functionality in llm.ts for product viability assessment.
- Implement product reading from Excel files in reader.ts.
- Stub SP-API integration in sp-api.ts for future implementation.
- Define TypeScript types in types.ts for product and analysis data structures.
- Write results to console and CSV in writer.ts.
- Configure TypeScript settings in tsconfig.json for project compilation.

src/types.ts

@@ -0,0 +1,59 @@
+export interface ProductRecord {
+  asin: string;
+  name: string;
+  unitCost: number;
+  brand?: string;
+  category?: string;
+  amazonRank?: number;
+  fbaNet?: number;
+  grossProfit?: number;
+  grossProfitPct?: number;
+  moq?: number;
+  moqCost?: number;
+  totalQtyAvail?: number;
+
+  link?: string;
+  [key: string]: unknown;
+}
+
+export interface KeepaData {
+  currentPrice: number | null;
+  avgPrice90: number | null;
+  minPrice90: number | null;
+  maxPrice90: number | null;
+  salesRank: number | null;
+  salesRankAvg90: number | null;
+  salesRankDrops30: number | null;
+  salesRankDrops90: number | null;
+  sellerCount: number | null;
+  buyBoxSeller: string | null;
+  buyBoxPrice: number | null;
+  monthlySold: number | null;
+  categoryTree: string[];
+}
+
+export interface SpApiData {
+  fbaFee: number;
+  fbmFee: number;
+  referralFeePercent: number;
+  estimatedSalePrice: number;
+}
+
+export interface EnrichedProduct {
+  record: ProductRecord;
+  keepa: KeepaData | null;
+  spApi: SpApiData;
+  fetchedAt: string;
+}
+
+export interface LlmVerdict {
+  asin: string;
+  verdict: "FBA" | "FBM" | "SKIP";
+  confidence: number;
+  reasoning: string;
+}
+
+export interface AnalysisResult {
+  product: EnrichedProduct;
+  verdict: LlmVerdict;
+}