Mechanic Workshop Management App Development

I need a complete mechanic / two-wheeler workshop management app for a real bike/scooter shop in India (local PC install preferred).

What the software must do
Customers & vehicles — name, phone, WhatsApp, number plate, make/model
Appointments — daily shop capacity (green/yellow/red), book slots
Job cards — vehicle entry, status flow (received → work → ready → completed), bay/mechanic
Manual labour & parts — enter service name + ₹ per job (no fixed price catalogue required)
Extra repairs — draft WhatsApp for customer approval, then add to estimate/bill
Estimates & invoices — GST (e.g. 18%), discount, advance payment, balance due
Owner bill approval — owner must approve bill before final invoice
WhatsApp messages — click-to-chat drafts (received, estimate, ready for pickup, invoice) with correct amount including tax
Search — English + spoken Telugu spelling (e.g. kastamar, gaadi, billu)
EN / తెలుగు language switch
Reports — basic revenue / outstanding
Settings — shop name, GST %, capacity, branding/photos optional
Offline / local — run on one Windows PC (backend + frontend), simple install
Tech preference (flexible if you deliver the same result)
Frontend: React (Vite)
Backend: Python FastAPI + SQLite
Clean UI suitable for a mechanic shop (bright, easy for shop staff)
Deliverables
Working app installed on my PC
Source code
Short how-to (EN + simple steps)
15–30 days bug-fix support after delivery
Budget
₹15,000 – ₹20,000 fixed price preferred (milestone-based).

Important
Amounts on Jobs list and WhatsApp must show total with tax
Capacity must count vehicles already in the shop, not only appointments
Must be usable by shop staff with low computer knowledge
Please include in your bid:

Similar shop / billing apps you built
Delivery time
Whether you can do install + training on Windows
Suggested Freelancer settings