Build an e-signature tool for light business use. Core features: 1. PDF upload with drag-and-drop placement of signature, date, name, and checkbox fields. 2. Multi-signer support with a defined signing order. 3. Email sign requests with a secure token link so signers do not need accounts. 4. Signature capture via typed, drawn, or uploaded signature, with an AI option that formats a typed name into a clean signature style. 5. An immutable audit trail: timestamps, IP address, email verification, and document hash per event. 6. A template library where AI pre-detects likely signature and date spots in common documents like NDAs and offer letters. 7. AI plain-language summaries of what the signer is agreeing to, generated from the document text. 8. A signed PDF with an appended certificate of completion, plus webhook notifications when documents are viewed, signed, or declined.