Add three new native modules (fswatch, sysinfo, udp) to the Wren CLI build system and module registry. Extend the io module with async file copy and move operations using libuv uv_fs_copyfile and uv_fs_rename, plus expose stat mtime/atime/ctime fields and stdin windowSize. Update the io.wren wrapper with File.write, File.copy, File.move static methods and corresponding foreign declarations. Add shebang lines to generator2.wren, merge_all_wren.wren, merge_docs.wren, and phonebook.wren scripts.
Introduce three new Makefile targets: `create_docs` to merge HTML manual files into a single markdown document using a new wren script, `create_training_data` to generate JSONL training and validation datasets from the manual, and `install` to copy the wren_cli binary to /usr/local/bin.
