Fix validation and exception handling bugs - Throw InvalidOperationException for duplicate state configuration - Throw InvalidOperationException for duplicate trigger in same state - Run all actions and throw AggregateException on failure, ensuring state consistency (exit failure = unchanged, entry failure = changed) - Validate null actions with ArgumentNullException.ThrowIfNull - Change Rule action lists to IReadOnlyList to prevent external mutation - Use state name in error messages f...

Fix validation and exception handling bugs - Throw InvalidOperationException for duplicate state configuration - Throw InvalidOperationException for duplicate trigger in same state - Run all actions and throw AggregateException on failure, ensuring state consistency (exit failure = unchanged, entry failure = changed) - Validate null actions with ArgumentNullException.ThrowIfNull - Change Rule action lists to IReadOnlyList to prevent external mutation - Use state name in error messages f... #66