feat: add core backend modules, inventory services, and patch scripts for AI Pharmacy API

scratch/test_inventory_endpoints.ts

@@ -0,0 +1,15 @@
+import { InventoryService } from '../src/modules/inventory/service';
+import { pool } from '../src/db/pool';
+
+async function testInventory() {
+  const service = new InventoryService();
+  const testTenant = 'act_admin';
+
+  const items = await service.getAllStockBatches(500, testTenant);
+  console.log(`Inventory Items count for ${testTenant}:`, items.length);
+  console.log('Sample item:', items[0]);
+
+  await pool.end();
+}
+
+testInventory().catch(console.error);