Implement the `round` method on the Num class in the Wren VM, which rounds a number to the nearest integer using standard rounding rules (away from zero for .5). The implementation adds a new `DEF_NUM_FN(round, round)` macro invocation in `wren_core.c`, registers the corresponding primitive `num_round`, and includes comprehensive documentation in the core module reference. A new test file `test/core/number/round.wren` validates behavior for positive, negative, zero, and fractional values. Also adds Kyle Charters to the AUTHORS file.