Design car rental schema and APIs

Design a car rental platform focusing on core entities, relational database schema, and API interfaces. Define key entities and relationships (e.g., customer, vehicle, vehicle_type, branch/location, inventory/unit, reservation, rental/contract, payment, pricing rule, promotion, insurance, availability/hold, staff, damage report). Propose table definitions with primary/foreign keys, unique constraints, and essential indexes (e.g., availability lookups by location and date). Describe workflows and consistency requirements for: search availability by location and date/time windows; create/modify/cancel reservation with holds to prevent double-booking; pick-up (vehicle assignment, contracts, inspection) and return (mileage, fuel, damage, late fees); pricing (base rate, mileage, insurance add-ons, taxes, promotions); payments (authorization, capture, refunds). Provide 3–5 representative REST endpoints with request/response fields (e.g., POST /search, POST /reservations, PATCH /reservations/{id}, POST /rentals/{id}/return). Discuss idempotency, pagination, authentication/authorization, concurrency control (row locks or optimistic versioning), and a plan to scale (read replicas, partitioning by branch/region, caching hot availability queries).