Initial commit: Complete Shopify Price Updater implementation

- Full Node.js application with Shopify GraphQL API integration
- Compare At price support for promotional pricing
- Comprehensive error handling and retry logic
- Progress tracking with markdown logging
- Complete test suite with unit and integration tests
- Production-ready with proper exit codes and signal handling

test-caching.js

@@ -0,0 +1,35 @@
+// Test the getConfig function with caching
+const { getConfig } = require("./src/config/environment");
+
+console.log("Testing getConfig with caching...\n");
+
+// Set up valid environment
+process.env.SHOPIFY_SHOP_DOMAIN = "test-shop.myshopify.com";
+process.env.SHOPIFY_ACCESS_TOKEN = "test-token-123456789";
+process.env.TARGET_TAG = "sale";
+process.env.PRICE_ADJUSTMENT_PERCENTAGE = "10";
+
+try {
+	console.log("First call to getConfig():");
+	const config1 = getConfig();
+	console.log("✅ Config loaded:", {
+		shopDomain: config1.shopDomain,
+		targetTag: config1.targetTag,
+		priceAdjustmentPercentage: config1.priceAdjustmentPercentage,
+	});
+
+	console.log("\nSecond call to getConfig() (should use cache):");
+	const config2 = getConfig();
+	console.log("✅ Config loaded from cache:", {
+		shopDomain: config2.shopDomain,
+		targetTag: config2.targetTag,
+		priceAdjustmentPercentage: config2.priceAdjustmentPercentage,
+	});
+
+	console.log("\nVerifying same object reference (caching):");
+	console.log("Same object?", config1 === config2 ? "✅ Yes" : "❌ No");
+} catch (error) {
+	console.log("❌ Error:", error.message);
+}
+
+console.log("\nCaching test completed!");