used car spare parts selling and for building maintenance services

System description I want a system for used car spare parts selling and for building maintenance services “Separate projects” and possibility to add more projects. Works as website, web app, android mobile app, iOS mobile app. Modern, user-friendly design. Option for working online or offline. Modern Authentication methods suitable for each type of applications. I want detailed proposal for the system before starting work in the system building. Registration Page: Mobile Number is mandatory and email is optional. User types: Visitor in website, Normal users (minimum credential is provided), Gold User (full credential is provided), and Approved user (Introduce prove of his personality such as official Ids). Possibility to add more user types. Chatting system: For users, and public conversation. Documents, files, images sharing between users. Rating and feedback System: Users and visitors for each other, products and services. Employees Management system: All employees registered users. Paid hourly based, daily based, monthly based, yearly based, contract based. Work time rate depends on groups and each employees and could be change by system manager. Schedule work time between employees, possible to exchange time between employees. Possible to allocate time by employees for their work time. Inventory management system: For used car and cement products. Cash Fallow system: For paying and collecting. Invoicing System: For sales. Financial statements reports: Any time based, daily based, monthly based and yearly based. Orders and delivering management system: Printing packing sticker, delivery note, map and location providing for users and customer. QR code for location possible to scan from sticker. Search: Search in products, services, users, advertisement, rating and chatting history. Advertisement section: Tab or part of page for advertisement. Registered Visitors and users can advertise free and chargeable Add. Code: Robust open source code and easy to read and amend buy us. Possible to be decoded and encoded. Provide guidance for setup and installing website web application mobile apps.