Zig support
https://github.com/ziglang/zig/issues/8633

- [x] `w4 new`: Add new project template
- [x] `w4 watch`: Add new filename suffix + build/run support
- [x] `w4 png2src`: Add new language parameter
- [x] Website: Setup documentation
- [x] Website: Translated code snippets for all guide pages