Add the `list_add` primitive to support appending elements to lists with automatic capacity management using `LIST_MIN_CAPACITY` and `LIST_GROW_FACTOR` constants. Rename internal `valuesEqual` and `reallocate` functions to `wrenValuesEqual` and `wrenReallocate` for consistent naming, and introduce `wrenPrintValue` to handle formatted output of all value types including lists. Add a test file `test/list_add.wren` verifying basic add operations and return value behavior.
