Refactor: Fully migrated to direct PostgreSQL, implemented Public API v1, fixed Vercel deployment conflicts, and updated documentation

lib/api-auth.ts

@@ -0,0 +1,21 @@
+import { db } from './db';
+
+export async function validateApiKey(apiKey: string | null) {
+  if (!apiKey) return null;
+
+  try {
+    const result = await db.query(
+      'SELECT * FROM merchants WHERE api_key = $1 LIMIT 1',
+      [apiKey]
+    );
+
+    if (result.rows.length === 0) {
+      return null;
+    }
+
+    return result.rows[0];
+  } catch (error) {
+    console.error('API Key Validation Error:', error);
+    return null;
+  }
+}