Add Prettier cache

[WuMingDao]

I find the .gitignore file has an optional eslint cache, not the eslint command, but has pretty. I wish maybe the pretty command should cache.

[olegpix]

Thanks for the PR! Enabling prettier --cache is a solid idea and should speed up repeated runs.

One small mismatch though: the PR adds /.prettier-cache to .gitignore, but Prettier’s cache location (when using --cache) is not the project root by default - it typically writes to node_modules/.cache/prettier/.prettier-cache unless --cache-location is provided. So that .gitignore entry likely won’t be used as-is.

Please, keep --cache and remove /.prettier-cache from .gitignore (the cache ends up under node_modules, which is usually ignored anyway).