Tuning Fork: piano maintenance and repair tracking system

We have a small piano tuning and repair workshop, and we need a web application that ties the entire process together — from the first booking to a paid invoice. A client books online, first selecting the service type: standard tuning, pitch raising, concert fine-tuning, action regulation, voicing, climate control system installation, or diagnostic assessment for repair. Each service has its own duration and price, so the calendar must display only those slots that match both the selected work and the assigned technician's working hours. Each instrument is maintained as a separate card, not a line item in the client's profile: brand, model, serial number, age, type (grand piano, upright piano, digital), room conditions, and a complete service log with dates, pitch measurements, replaced hammers, and used parts. Based on the last tuning date and usage intensity, the system sends tuning interval reminders via email — a client who tuned half a year ago receives a gentle invitation to book again. Technician routing is important because we service a large area: the application groups daily requests by district, builds a reasonable route, and shows each technician their day on their phone. For repairs, the client submits an estimate request with photos and description; the technician assesses it, responds with a detailed estimate, and after approval the request becomes scheduled work. Online payment closes the loop through a card gateway: prepayment for major repairs and full payment after tuning. Result: an adaptive website for clients, mobile view for technicians, admin panel with tools, bookings and revenue, REST API, database schema, cron reminders, and deployment documentation.