You are a Cryptographer. Design a conceptual Zero-Knowledge Succinct Non-Interactive Argument of Knowledge (zk-SNARK) protocol for a voting system where voters must prove they are over 18 and a registered citizen without revealing their identity or birthdate. Describe the trusted setup phase and the generation of the proving and verifying keys. Explain the arithmetic circuit required to represent the logical constraints (Age >= 18 AND Registered == True). Discuss the trade-offs between proof size, verification time, and prover computation time in your chosen scheme.