Inventory Management Software – Review, Fix & Complete Existing Web Application

I have already developed a web-based Inventory Management System for my business using AI assistance (Claude).
Website: scopeenterprises.in
The system currently includes modules such as:
Dashboard with stock summary
Stock Balance
Purchase Entry
Sales Entry
Purchase & Sales Reports
Expiry Alerts
Negative/Zero Stock Alerts
Products & Suppliers
Customers
Daily Tasks
Quotation
Backup & Restore
Settings
Stock by Category
Batch-wise stock tracking
Short-expiry product tracking
I am looking for an experienced Full-Stack Web Developer to review the existing application, understand the current code/database structure, fix bugs, improve the functionality and UI, and make the system stable and production-ready.
Important: I already have the software developed. I am not looking to build a completely new application from scratch. The freelancer should work on the existing system and improve/complete it.
Work Required
Review existing source code and database
Identify and fix existing bugs
Check all modules and workflows
Improve inventory calculations and stock movement
Verify Purchase → Stock → Sales flow
Batch number and expiry-date management
Low-stock and expiry alerts
Improve reports and search/filter options
User login and access control
Database backup and restore
Improve dashboard and UI/UX
Mobile/tablet responsive design
Improve website speed and security
Proper error handling and validation
Deployment/server configuration
Final testing and documentation