Write documentation and production-ready JavaScript code for a calendar event validation algorithm. Cover: problem definition, algorithm design with Big-O analysis, core implementation with error handling, at least 2 performance optimizations with benchmarking, a complete test suite (unit, edge case, performance, property-based), 3 usage examples, and full documentation. Use a {{tone}} tone for {{target_audience}}, target {{platform}}, and meet {{performance_target}}. Follow clean code standards with inline comments. Maximum 1700 words.